Chapter 4. MySQL Programs

Table of Contents

4.1. Overview of MySQL Programs
4.2. Using MySQL Programs
4.2.1. Invoking MySQL Programs
4.2.2. Connecting to the MySQL Server
4.2.3. Specifying Program Options
4.2.4. Setting Environment Variables
4.3. MySQL Server and Server-Startup Programs
4.3.1. mysqld — The MySQL Server
4.3.2. mysqld_safe — MySQL Server Startup Script
4.3.3. mysql.server — MySQL Server Startup Script
4.3.4. mysqld_multi — Manage Multiple MySQL Servers
4.4. MySQL Installation-Related Programs
4.4.1. comp_err — Compile MySQL Error Message File
4.4.2. make_win_bin_dist — Package MySQL Distribution as ZIP Archive
4.4.3. mysqlbug — Generate Bug Report
4.4.4. mysql_fix_privilege_tables — Upgrade MySQL System Tables
4.4.5. mysql_install_db — Initialize MySQL Data Directory
4.4.6. mysql_secure_installation — Improve MySQL Installation Security
4.4.7. mysql_tzinfo_to_sql — Load the Time Zone Tables
4.4.8. mysql_upgrade — Check Tables for MySQL Upgrade
4.5. MySQL Client Programs
4.5.1. mysql — The MySQL Command-Line Tool
4.5.2. mysqladmin — Client for Administering a MySQL Server
4.5.3. mysqlcheck — A Table Maintenance Program
4.5.4. mysqldump — A Database Backup Program
4.5.5. mysqlimport — A Data Import Program
4.5.6. mysqlshow — Display Database, Table, and Column Information
4.5.7. mysqlslap — Load Emulation Client
4.6. MySQL Administrative and Utility Programs
4.6.1. innochecksum — Offline InnoDB File Checksum Utility
4.6.2. myisam_ftdump — Display Full-Text Index information
4.6.3. myisamchk — MyISAM Table-Maintenance Utility
4.6.4. myisamlog — Display MyISAM Log File Contents
4.6.5. myisampack — Generate Compressed, Read-Only MyISAM Tables
4.6.6. mysqlaccess — Client for Checking Access Privileges
4.6.7. mysqlbackup — Display Backup Information
4.6.8. mysqlbinlog — Utility for Processing Binary Log Files
4.6.9. mysqldumpslow — Summarize Slow Query Log Files
4.6.10. mysqlhotcopy — A Database Backup Program
4.6.11. mysql_convert_table_format — Convert Tables to Use a Given Storage Engine
4.6.12. mysql_find_rows — Extract SQL Statements from Files
4.6.13. mysql_fix_extensions — Normalize Table File Name Extensions
4.6.14. mysql_setpermission — Interactively Set Permissions in Grant Tables
4.6.15. mysql_waitpid — Kill Process and Wait for Its Termination
4.6.16. mysql_zap — Kill Processes That Match a Pattern
4.7. MySQL Program Development Utilities
4.7.1. msql2mysql — Convert mSQL Programs for Use with MySQL
4.7.2. mysql_config — Get Compile Options for Compiling Clients
4.7.3. my_print_defaults — Display Options from Option Files
4.7.4. resolve_stack_dump — Resolve Numeric Stack Trace Dump to Symbols
4.8. Miscellaneous Programs
4.8.1. perror — Explain Error Codes
4.8.2. replace — A String-Replacement Utility
4.8.3. resolveip — Resolve Host name to IP Address or Vice Versa

This chapter provides a brief overview of the MySQL command-line programs provided by Sun Microsystems, Inc. It also discusses the general syntax for specifying options when you run these programs. Most programs have options that are specific to their own operation, but the option syntax is similar for all of them. Finally, the chapter provides more detailed descriptions of individual programs, including which options they recognize.

4.1. Overview of MySQL Programs

There are many different programs in a MySQL installation. This section provides a brief overview of them. Later sections provide a more detailed description of each one. Each program's description indicates its invocation syntax and the options that it supports.

Most MySQL distributions include all of these programs, except for those programs that are platform-specific. (For example, the server startup scripts are not used on Windows.) The exception is that RPM distributions are more specialized. There is one RPM for the server, another for client programs, and so forth. If you appear to be missing one or more programs, see Chapter 2, Installing and Upgrading MySQL, for information on types of distributions and what they contain. It may be that you have a distribution that does not include all programs and you need to install an additional package.

Each MySQL program takes many different options. Most programs provide a --help option that you can use to get a description of the program's different options. For example, try mysql --help.

You can override default option values for MySQL programs by specifying options on the command line or in an option file. See Section 4.2, “Using MySQL Programs”, for general information on invoking programs and specifying program options.

The MySQL server, mysqld, is the main program that does most of the work in a MySQL installation. The server is accompanied by several related scripts that assist you in starting and stopping the server:

Several programs perform setup operations during MySQL installation or upgrading:

MySQL client programs that connect to the MySQL server:

MySQL administrative and utility programs:

MySQL program-development utilities:

Miscellaneous utilities:

Sun Microsystems, Inc. also provides several GUI tools for administering and otherwise working with MySQL Server:

  • MySQL Workbench: This is the latest graphical tool for working with MySQL databases.

  • MySQL Administrator: This tool is used for administering MySQL servers, databases, tables, and user accounts.

  • MySQL Query Browser: This graphical tool is used for creating, executing, and optimizing queries on MySQL databases.

  • MySQL Migration Toolkit: This tool helps you migrate schemas and data from other relational database management systems for use with MySQL.

These GUI programs are available at http://dev.mysql.com/downloads/. Each has its own manual that you can access at http://dev.mysql.com/doc/.

MySQL client programs that communicate with the server using the MySQL client/server library use the following environment variables.

MYSQL_UNIX_PORTThe default Unix socket file; used for connections to localhost
MYSQL_TCP_PORTThe default port number; used for TCP/IP connections
MYSQL_PWDThe default password
MYSQL_DEBUGDebug trace options when debugging
TMPDIRThe directory where temporary tables and files are created

For a full list of environment variables used by MySQL programs, see Section 2.13, “Environment Variables”.

Use of MYSQL_PWD is insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

4.2. Using MySQL Programs

4.2.1. Invoking MySQL Programs

To invoke a MySQL program from the command line (that is, from your shell or command prompt), enter the program name followed by any options or other arguments needed to instruct the program what you want it to do. The following commands show some sample program invocations. “shell>” represents the prompt for your command interpreter; it is not part of what you type. The particular prompt you see depends on your command interpreter. Typical prompts are $ for sh or bash, % for csh or tcsh, and C:\> for the Windows command.com or cmd.exe command interpreters.

shell> mysql --user=root test
shell> mysqladmin extended-status variables
shell> mysqlshow --help
shell> mysqldump -u root personnel

Arguments that begin with a single or double dash (“-”, “--”) specify program options. Options typically indicate the type of connection a program should make to the server or affect its operational mode. Option syntax is described in Section 4.2.3, “Specifying Program Options”.

Nonoption arguments (arguments with no leading dash) provide additional information to the program. For example, the mysql program interprets the first nonoption argument as a database name, so the command mysql --user=root test indicates that you want to use the test database.

Later sections that describe individual programs indicate which options a program supports and describe the meaning of any additional nonoption arguments.

Some options are common to a number of programs. The most frequently used of these are the --host (or -h), --user (or -u), and --password (or -p) options that specify connection parameters. They indicate the host where the MySQL server is running, and the user name and password of your MySQL account. All MySQL client programs understand these options; they allow you to specify which server to connect to and the account to use on that server. Other connection options are --port (or -P) to specify a TCP/IP port number and --socket (or -S) to specify a Unix socket file on Unix (or named pipe name on Windows). For more information on options that specify connection options, see Section 4.2.2, “Connecting to the MySQL Server”.

You may find it necessary to invoke MySQL programs using the path name to the bin directory in which they are installed. This is likely to be the case if you get a “program not found” error whenever you attempt to run a MySQL program from any directory other than the bin directory. To make it more convenient to use MySQL, you can add the path name of the bin directory to your PATH environment variable setting. That enables you to run a program by typing only its name, not its entire path name. For example, if mysql is installed in /usr/local/mysql/bin, you can run the program by invoking it as mysql, and it is not necessary to invoke it as /usr/local/mysql/bin/mysql.

Consult the documentation for your command interpreter for instructions on setting your PATH variable. The syntax for setting environment variables is interpreter-specific. (Some information is given in Section 4.2.4, “Setting Environment Variables”.) After modifying your PATH setting, open a new console window on Windows or log in again on Unix so that the setting goes into effect.

4.2.2. Connecting to the MySQL Server

For a client program to be able to connect to the MySQL server, it must use the proper connection parameters, such as the name of the host where the server is running and the user name and password of your MySQL account. Each connection parameter has a default value, but you can override them as necessary using program options specified either on the command line or in an option file.

The examples here use the mysql client program, but the principles apply to other clients such as mysqldump, mysqladmin, or mysqlshow.

This command invokes mysql without specifying any connection parameters explicitly:

shell> mysql

Because there are no parameter options, the default values apply:

  • The default host name is localhost. On Unix, this has a special meaning, as described later.

  • The default user name is ODBC on Windows or your Unix login name on Unix.

  • No password is sent if neither -p nor --password is given.

  • For mysql, the first nonoption argument is taken as the name of the default database. If there is no such option, mysql does not select a default database.

To specify the host name and user name explicitly, as well as a password, supply appropriate options on the command line:

shell> mysql --host=localhost --user=myname --password=mypass mydb
shell> mysql -h localhost -u myname -pmypass mydb

For password options, the password value is optional:

  • If you use a -p or --password option and specify the password value, there must be no space between -p or --password= and the password following it.

  • If you use a -p or --password option but do not specify the password value, the client program prompts you to enter the password. The password is not displayed as you enter it. This is more secure than giving the password on the command line. Other users on your system may be able to see a password specified on the command line by executing a command such as ps auxw. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

As just mentioned, including the password value on the command line can be a security risk. To avoid this problem, specify the --password or -p option without any following password value:

shell> mysql --host=localhost --user=myname --password mydb
shell> mysql -h localhost -u myname -p mydb

When the password option has no password value, the client program prints a prompt and waits for you to enter the password. (In these examples, mydb is not interpreted as a password because it is separated from the preceding password option by a space.)

On some systems, the library routine that MySQL uses to prompt for a password automatically limits the password to eight characters. That is a problem with the system library, not with MySQL. Internally, MySQL does not have any limit for the length of the password. To work around the problem, change your MySQL password to a value that is eight or fewer characters long, or put your password in an option file.

On Unix, MySQL programs treat the host name localhost specially, in a way that is likely different from what you expect compared to other network-based programs. For connections to localhost, MySQL programs attempt to connect to the local server by using a Unix socket file. This occurs even if a --port or -P option is given to specify a port number. To ensure that the client makes a TCP/IP connection to the local server, use --host or -h to specify a host name value of 127.0.0.1, or the IP address or name of the local server. You can also specify the connection protocol explicitly, even for localhost, by using the --protocol=TCP option. For example:

shell> mysql --host=127.0.0.1
shell> mysql --protocol=TCP

The --protocol option enables you to establish a particular type of connection even when the other options would normally default to some other protocol.

On Windows, you can force a MySQL client to use a named-pipe connection by specifying the --pipe or --protocol=PIPE option, or by specifying . (period) as the host name. If named-pipe connections are not enabled, an error occurs. Use the --socket option to specify the name of the pipe if you do not want to use the default pipe name.

Connections to remote servers always use TCP/IP. This command connects to the server running on remote.example.com using the default port number (3306):

shell> mysql --host=remote.example.com

To specify a port number explicitly, use the --port or -P option:

shell> mysql --host=remote.example.com --port=13306

You can specify a port number for connections to a local server, too. However, as indicated previously, connections to localhost on Unix will use a socket file by default. You will need to force a TCP/IP connection as already described or any option that specifies a port number will be ignored.

For this command, the program uses a socket file on Unix and the --port option is ignored:

shell> mysql --port=13306 --host=localhost

To cause the port number to be used, invoke the program in either of these ways:

shell> mysql --port=13306 --host=127.0.0.1
shell> mysql --port=13306 --protocol=TCP

The following list summarizes the options that can be used to control how client programs connect to the server:

  • --host=host_name, -h host_name

    The host where the server is running. The default value is localhost.

  • --password[=pass_val], -p[pass_val]

    The password of the MySQL account. As described earlier, the password value is optional, but if given, there must be no space between -p or --password= and the password following it. The default is to send no password.

  • --pipe, -W

    On Windows, connect to the server via a named pipe. This option applies only for connections to a local server. The server must be started with the --enable-named-pipe option to enable named-pipe connections.

  • --port=port_num, -P port_num

    The port number to use for the connection, for connections made via TCP/IP. The default port number is 3306.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    This option explicitly specifies a protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For example, connections on Unix to localhost are made via a Unix socket file by default:

    shell> mysql --host=localhost
    

    To force a TCP/IP connection to be used instead, specify a --protocol option:

    shell> mysql --host=localhost --protocol=TCP
    

    The following table shows the allowable --protocol option values and indicates the platforms on which each value may be used. The values are not case sensitive.

    --protocol ValueConnection ProtocolAllowable Operating Systems
    TCPTCP/IP connection to local or remote serverAll
    SOCKETUnix socket file connection to local serverUnix only
    PIPENamed-pipe connection to local serverWindows only
    MEMORYShared-memory connection to local serverWindows only
  • --shared-memory-base-name=name

    On Windows, the shared-memory name to use, for connections made via shared memory to a local server. The default value is MYSQL. The shared-memory name is case sensitive.

    The server must be started with the --shared-memory option to enable shared-memory connections.

  • --socket=file_name, -S file_name

    On Unix, the name of the Unix socket file to use, for connections made via a named pipe to a local server. The default Unix socket file name is /tmp/mysql.sock.

    On Windows, the name of the named pipe to use, for connections to a local server. The default Windows pipe name is MySQL. The pipe name is not case sensitive.

    The server must be started with the --enable-named-pipe option to enable named-pipe connections.

  • --ssl*

    Options that begin with --ssl are used for establishing a secure connection to the server via SSL, if the server is configured with SSL support. For details, see Section 5.5.7.3, “SSL Command Options”.

  • --user=user_name, -u user_name

    The user name of the MySQL account you want to use. The default user name is ODBC on Windows or your Unix login name on Unix.

It is possible to specify different default values to be used when you make a connection so that you need not enter them on the command line each time you invoke a client program. This can be done in a couple of ways:

4.2.3. Specifying Program Options

There are several ways to specify options for MySQL programs:

  • List the options on the command line following the program name. This is most common for options that apply to a specific invocation of the program.

  • List the options in an option file that the program reads when it starts. This is common for options that you want the program to use each time it runs.

  • List the options in environment variables (see Section 4.2.4, “Setting Environment Variables”). This method is useful for options that you want to apply each time the program runs. In practice, option files are used more commonly for this purpose, but Section 5.6.2, “Running Multiple Servers on Unix”, discusses one situation in which environment variables can be very helpful. It describes a handy technique that uses such variables to specify the TCP/IP port number and Unix socket file for the server and for client programs.

MySQL programs determine which options are given first by examining environment variables, then by reading option files, and then by checking the command line. This means that environment variables have the lowest precedence and command-line options the highest.

Because options are processed in order, if an option is specified multiple times, the last occurrence takes precedence. The following command causes mysql to connect to the server running on localhost:

shell> mysql -h example.com -h localhost

If conflicting or related options are given, later options take precedence over earlier options. The following command runs mysql in “no column names” mode:

shell> mysql --column-names --skip-column-names

An option can be specified by writing it in full or as any unambiguous prefix. For example, the --compress option can be given to mysqldump as --compr, but not as --comp because the latter is ambiguous:

shell> mysqldump --comp
mysqldump: ambiguous option '--comp' (compatible, compress)

Be aware that the use of option prefixes can cause problems in the event that new options are implemented for a program. A prefix that is unambiguous now might become ambiguous in the future.

You can take advantage of the way that MySQL programs process options by specifying default values for a program's options in an option file. That enables you to avoid typing them each time you run the program, but also allows you to override the defaults if necessary by using command-line options.

4.2.3.1. Using Options on the Command Line

Program options specified on the command line follow these rules:

  • Options are given after the command name.

  • An option argument begins with one dash or two dashes, depending on whether it is a short form or long form of the option name. Many options have both short and long forms. For example, -? and --help are the short and long forms of the option that instructs a MySQL program to display its help message.

  • Option names are case sensitive. -v and -V are both legal and have different meanings. (They are the corresponding short forms of the --verbose and --version options.)

  • Some options take a value following the option name. For example, -h localhost or --host=localhost indicate the MySQL server host to a client program. The option value tells the program the name of the host where the MySQL server is running.

  • For a long option that takes a value, separate the option name and the value by an “=” sign. For a short option that takes a value, the option value can immediately follow the option letter, or there can be a space between: -hlocalhost and -h localhost are equivalent. An exception to this rule is the option for specifying your MySQL password. This option can be given in long form as --password=pass_val or as --password. In the latter case (with no password value given), the program prompts you for the password. The password option also may be given in short form as -ppass_val or as -p. However, for the short form, if the password value is given, it must follow the option letter with no intervening space. The reason for this is that if a space follows the option letter, the program has no way to tell whether a following argument is supposed to be the password value or some other kind of argument. Consequently, the following two commands have two completely different meanings:

    shell> mysql -ptest
    shell> mysql -p test
    

    The first command instructs mysql to use a password value of test, but specifies no default database. The second instructs mysql to prompt for the password value and to use test as the default database.

  • Within option names, dash (“-”) and underscore (“_”) may be used interchangeably. For example, --skip-grant-tables and --skip_grant_tables are equivalent. (However, the leading dashes cannot be given as underscores.)

Another option that may occasionally be useful with mysql is the --execute or -e option, which can be used to pass SQL statements to the server. When this option is used, mysql executes the statements and exits. The statements must be enclosed by quotation marks. For example, you can use the following command to obtain a list of user accounts:

shell> mysql -u root -p --execute="SELECT User, Host FROM user" mysql
Enter password: ******
+------+-----------+
| User | Host      |
+------+-----------+
|      | gigan     |
| root | gigan     |
|      | localhost |
| jon  | localhost |
| root | localhost |
+------+-----------+
shell>

Note that the long form (--execute) is followed by an equals sign (=).

If you wish to use quoted values within a statement, you will either need to escape the inner quotes, or use a different type of quotes within the statement from those used to quote the statement itself. The capabilities of your command processor dictate your choices for whether you can use single or double quotation marks and the syntax for escaping quote characters. For example, if your command processor supports quoting with single or double quotes, you can double quotes around the statement, and single quotes for any quoted values within the statement.

In the preceding example, the name of the mysql database was passed as a separate argument. However, the same statement could have been executed using this command, which specifies no default database:

mysql> mysql -u root -p --execute="SELECT User, Host FROM mysql.user"

Multiple SQL statements may be passed on the command line, separated by semicolons:

shell> mysql -u root -p -e "SELECT VERSION();SELECT NOW()"
Enter password: ******
+-----------------+
| VERSION()       |
+-----------------+
| 5.1.5-alpha-log |
+-----------------+
+---------------------+
| NOW()               |
+---------------------+
| 2006-01-05 21:19:04 |
+---------------------+

4.2.3.2. Program Option Modifiers

Some options are “boolean” and control behavior that can be turned on or off. For example, the mysql client supports a --column-names option that determines whether or not to display a row of column names at the beginning of query results. By default, this option is enabled. However, you may want to disable it in some instances, such as when sending the output of mysql into another program that expects to see only data and not an initial header line.

To disable column names, you can specify the option using any of these forms:

--disable-column-names
--skip-column-names
--column-names=0

The --disable and --skip prefixes and the =0 suffix all have the same effect: They turn the option off.

The “enabled” form of the option may be specified in any of these ways:

--column-names
--enable-column-names
--column-names=1

If an option is prefixed by --loose, a program does not exit with an error if it does not recognize the option, but instead issues only a warning:

shell> mysql --loose-no-such-option
mysql: WARNING: unknown option '--no-such-option'

The --loose prefix can be useful when you run programs from multiple installations of MySQL on the same machine and list options in an option file, An option that may not be recognized by all versions of a program can be given using the --loose prefix (or loose in an option file). Versions of the program that recognize the option process it normally, and versions that do not recognize it issue a warning and ignore it.

mysqld enables a limit to be placed on how large client programs can set dynamic system variables. To do this, use a --maximum prefix with the variable name. For example, --maximum-query_cache_size=4M prevents any client from making the query cache size larger than 4MB.

4.2.3.3. Using Option Files

Most MySQL programs can read startup options from option files (also sometimes called configuration files). Option files provide a convenient way to specify commonly used options so that they need not be entered on the command line each time you run a program. For the MySQL server, MySQL provides a number of preconfigured option files.

To determine whether a program reads option files, invoke it with the --help option. (For mysqld, use --verbose and --help.) If the program reads option files, the help message indicates which files it looks for and which option groups it recognizes.

On Windows, MySQL programs read startup options from the following files.

File NamePurpose
WINDIR\my.ini, WINDIR\my.cnfGlobal options
C:\my.ini, C:\my.cnfGlobal options
INSTALLDIR\my.ini, INSTALLDIR\my.cnfGlobal options
defaults-extra-fileThe file specified with --defaults-extra-file=path, if any

WINDIR represents the location of your Windows directory. This is commonly C:\WINDOWS. You can determine its exact location from the value of the WINDIR environment variable using the following command:

C:\> echo %WINDIR%

INSTALLDIR represents the MySQL installation directory. This is typically C:\PROGRAMDIR\MySQL\MySQL 6.0 Server where PROGRAMDIR represents the programs directory (usually Program Files on English-language versions of Windows), when MySQL 6.0 has been installed using the installation and configuration wizards. See The Location of the my.ini File.

On Unix, MySQL programs read startup options from the following files.

File NamePurpose
/etc/my.cnfGlobal options
/etc/mysql/my.cnfGlobal options
SYSCONFDIR/my.cnfGlobal options
$MYSQL_HOME/my.cnfServer-specific options
defaults-extra-fileThe file specified with --defaults-extra-file=path, if any
~/.my.cnfUser-specific options

SYSCONFDIR represents the directory specified with the --sysconfdir option to configure when MySQL was built. By default, this is the etc directory located under the compiled-in installation directory.

MYSQL_HOME is an environment variable containing the path to the directory in which the server-specific my.cnf file resides.

If MYSQL_HOME is not set and you start the server using the mysqld_safe program, mysqld_safe attempts to set MYSQL_HOME as follows:

  • Let BASEDIR and DATADIR represent the path names of the MySQL base directory and data directory, respectively.

  • If there is a my.cnf file in DATADIR but not in BASEDIR, mysqld_safe sets MYSQL_HOME to DATADIR.

  • Otherwise, if MYSQL_HOME is not set and there is no my.cnf file in DATADIR, mysqld_safe sets MYSQL_HOME to BASEDIR.

In MySQL 6.0, use of DATADIR as the location for my.cnf is deprecated.

Typically, DATADIR is /usr/local/mysql/data for a binary installation or /usr/local/var for a source installation. Note that this is the data directory location that was specified at configuration time, not the one specified with the --datadir option when mysqld starts. Use of --datadir at runtime has no effect on where the server looks for option files, because it looks for them before processing any options.

MySQL looks for option files in the order just described and reads any that exist. If an option file that you want to use does not exist, create it with a plain text editor.

If multiple instances of a given option are found, the last instance takes precedence. There is one exception: For mysqld, the first instance of the --user option is used as a security precaution, to prevent a user specified in an option file from being overridden on the command line.

Note

On Unix platforms, MySQL ignores configuration files that are world-writable. This is intentional as a security measure.

Any long option that may be given on the command line when running a MySQL program can be given in an option file as well. To get the list of available options for a program, run it with the --help option.

The syntax for specifying options in an option file is similar to command-line syntax, except that you omit the leading two dashes and you specify only one option per line. For example, --quick and --host=localhost on the command line should be specified as quick and host=localhost on separate lines in an option file. To specify an option of the form --loose-opt_name in an option file, write it as loose-opt_name.

Empty lines in option files are ignored. Nonempty lines can take any of the following forms:

  • #comment, ;comment

    Comment lines start with “#” or “;”. A “#” comment can start in the middle of a line as well.

  • [group]

    group is the name of the program or group for which you want to set options. After a group line, any option-setting lines apply to the named group until the end of the option file or another group line is given.

  • opt_name

    This is equivalent to --opt_name on the command line.

  • opt_name=value

    This is equivalent to --opt_name=value on the command line. In an option file, you can have spaces around the “=” character, something that is not true on the command line. You can enclose the value within single quotes or double quotes, which is useful if the value contains a “#” comment character or whitespace.

For options that take a numeric value, the value can be given with a suffix of K, M, or G (either uppercase or lowercase) to indicate a multiplier of 1024, 10242 or 10243. For example, the following command tells mysqladmin to ping the server 1024 times, sleeping 10 seconds between each ping:

mysql> mysqladmin --count=1K --sleep=10 ping

Leading and trailing blanks are automatically deleted from option names and values. You may use the escape sequences “\b”, “\t”, “\n”, “\r”, “\\”, and “\s” in option values to represent the backspace, tab, newline, carriage return, backslash, and space characters.

Because the “\\” escape sequence represents a single backslash, you must write each “\” as “\\”. Alternatively, you can specify the value using “/” rather than “\” as the path name separator.

If an option group name is the same as a program name, options in the group apply specifically to that program. For example, the [mysqld] and [mysql] groups apply to the mysqld server and the mysql client program, respectively.

The [client] option group is read by all client programs (but not by mysqld). This allows you to specify options that apply to all clients. For example, [client] is the perfect group to use to specify the password that you use to connect to the server. (But make sure that the option file is readable and writable only by yourself, so that other people cannot find out your password.) Be sure not to put an option in the [client] group unless it is recognized by all client programs that you use. Programs that do not understand the option quit after displaying an error message if you try to run them.

Here is a typical global option file:

[client]
port=3306
socket=/tmp/mysql.sock

[mysqld]
port=3306
socket=/tmp/mysql.sock
key_buffer_size=16M
max_allowed_packet=8M

[mysqldump]
quick

The preceding option file uses var_name=value syntax for the lines that set the key_buffer_size and max_allowed_packet variables.

Here is a typical user option file:

[client]
# The following password will be sent to all standard MySQL clients
password="my_password"

[mysql]
no-auto-rehash
connect_timeout=2

[mysqlhotcopy]
interactive-timeout

If you want to create option groups that should be read by mysqld servers from a specific MySQL release series only, you can do this by using groups with names of [mysqld-5.1], [mysqld-6.0], and so forth. The following group indicates that the --new option should be used only by MySQL servers with 6.0.x version numbers:

[mysqld-6.0]
new

It is possible to use !include directives in option files to include other option files and !includedir to search specific directories for option files. For example, to include the /home/mydir/myopt.cnf file, use the following directive:

!include /home/mydir/myopt.cnf

To search the /home/mydir directory and read option files found there, use this directive:

!includedir /home/mydir

There is no guarantee about the order in which the option files in the directory will be read.

Note

Currently, any files to be found and included using the !includedir directive on Unix operating systems must have file names ending in .cnf. On Windows, this directive checks for files with the .ini or .cnf extension.

Write the contents of an included option file like any other option file. That is, it should contain groups of options, each preceded by a [group] line that indicates the program to which the options apply.

While an included file is being processed, only those options in groups that the current program is looking for are used. Other groups are ignored. Suppose that a my.cnf file contains this line:

!include /home/mydir/myopt.cnf

And suppose that /home/mydir/myopt.cnf looks like this:

[mysqladmin]
force

[mysqld]
key_buffer_size=16M

If my.cnf is processed by mysqld, only the [mysqld] group in /home/mydir/myopt.cnf is used. If the file is processed by mysqladmin, only the [mysqldamin] group is used. If the file is processed by any other program, no options in /home/mydir/myopt.cnf are used.

The !includedir directive is processed similarly except that all option files in the named directory are read.

4.2.3.3.1. Command-Line Options that Affect Option-File Handling

Most MySQL programs that support option files handle the following options. They affect option-file handling, so they must be given on the command line and not in an option file. To work properly, each of these options must immediately follow the command name, with the exception that --print-defaults may be used immediately after --defaults-file or --defaults-extra-file. Also, when specifying file names, you should avoid the use of the “~” shell metacharacter because it might not be interpreted as you expect.

  • --defaults-extra-file=file_name

    Read this option file after the global option file but (on Unix) before the user option file. file_name is the full path name to the file. If the file does not exist or is otherwise inaccessible, the program will exit with an error.

  • --defaults-file=file_name

    Use only the given option file. file_name is the full path name to the file. If the file does not exist or is otherwise inaccessible, the program will exit with an error.

  • --defaults-group-suffix=str

    If this option is given, the program reads not only its usual option groups, but also groups with the usual names and a suffix of str. For example, the mysql client normally reads the [client] and [mysql] groups. If the --defaults-group-suffix=_other option is given, mysql also reads the [client_other] and [mysql_other] groups.

  • --no-defaults

    Do not read any option files. If a program does not start because it is reading unknown options from an option file, --no-defaults can be used to prevent the program from reading them.

  • --print-defaults

    Print the program name and all options that it gets from option files.

4.2.3.3.2. Preconfigured Option Files

MySQL provides a number of preconfigured option files that can be used as a basis for tuning the MySQL server. Look for files such as my-small.cnf, my-medium.cnf, my-large.cnf, and my-huge.cnf, which are sample option files for small, medium, large, and very large systems. On Windows, the extension is .ini rather than .cnf extension.

Note

On Windows, the .cnf or .ini option file extension might not be displayed.

For a binary distribution, look for the files in or under your installation directory. If you have a source distribution, look in the support-files directory. You can rename a copy of a sample file and place it in the appropriate location for use as a base configuration file. Regarding names and appropriate location, see the general information provided in Section 4.2.3.3, “Using Option Files”.

4.2.3.4. Using Options to Set Program Variables

Many MySQL programs have internal variables that can be set at runtime using the SET statement. See Section 12.5.5, “SET Syntax”, and Section 5.1.6, “Using System Variables”.

Most of these program variables also can be set at server startup by using the same syntax that applies to specifying program options. For example, mysql has a max_allowed_packet variable that controls the maximum size of its communication buffer. To set the max_allowed_packet variable for mysql to a value of 16MB, use either of the following commands:

shell> mysql --max_allowed_packet=16777216
shell> mysql --max_allowed_packet=16M

The first command specifies the value in bytes. The second specifies the value in megabytes. For variables that take a numeric value, the value can be given with a suffix of K, M, or G (either uppercase or lowercase) to indicate a multiplier of 1024, 10242 or 10243. (For example, when used to set max_allowed_packet, the suffixes indicate units of kilobytes, megabytes, or gigabytes.)

In an option file, variable settings are given without the leading dashes:

[mysql]
max_allowed_packet=16777216

Or:

[mysql]
max_allowed_packet=16M

If you like, underscores in a variable name can be specified as dashes. The following option groups are equivalent. Both set the size of the server's key buffer to 512MB:

[mysqld]
key_buffer_size=512M

[mysqld]
key-buffer-size=512M

A variable can be specified by writing it in full or as any unambiguous prefix. For example, the max_allowed_packet variable can be set for mysql as --max_a, but not as --max because the latter is ambiguous:

shell> mysql --max=1000000
mysql: ambiguous option '--max=1000000' (max_allowed_packet, max_join_size)

Be aware that the use of variable prefixes can cause problems in the event that new variables are implemented for a program. A prefix that is unambiguous now might become ambiguous in the future.

Suffixes for specifying a value multiplier can be used when setting a variable at server startup, but not to set the value with SET at runtime. On the other hand, with SET you can assign a variable's value using an expression, which is not true when you set a variable at server startup. For example, the first of the following lines is legal at server startup, but the second is not:

shell> mysql --max_allowed_packet=16M
shell> mysql --max_allowed_packet=16*1024*1024

Conversely, the second of the following lines is legal at runtime, but the first is not:

mysql> SET GLOBAL max_allowed_packet=16M;
mysql> SET GLOBAL max_allowed_packet=16*1024*1024;

Note

Before MySQL 4.0.2, the only syntax for setting program variables was --set-variable=option=value (or set-variable=option=value in option files). Underscores cannot be given as dashes, and the variable name must be specified in full. This syntax still is recognized, but is now deprecated.

4.2.3.5. Option Defaults, Options Expecting Values, and the = Sign

By convention, long forms of options that assign a value are written with an equals (=) sign, like this:

shell> mysql --host=tonfisk --user=jon

For options that require a value (that is, not having a default value), the equals sign is not required, and so the following is also valid:

shell> mysql --host tonfisk --user jon

In both cases, the mysql client attempts to connect to a MySQL server running on the host named “tonfisk” using an account with the user name “jon”.

Due to this behavior, problems can occasionally arise when no value is provided for an option that expects one. Consider the following example, where a user connects to a MySQL server running on host tonfisk as user jon:

shell> mysql --host 85.224.35.45 --user jon
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 6.0.12 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> SELECT CURRENT_USER();
+----------------+
| CURRENT_USER() |
+----------------+
| jon@%          |
+----------------+
1 row in set (0.00 sec)

Omitting the required value for one of these option yields an error, such as the one shown here:

shell> mysql --host 85.224.35.45 --user
mysql: option '--user' requires an argument

In this case, mysql was unable to find a value following the --user option because nothing came after it on the command line. However, if you omit the value for an option that is not the last option to be used, you obtain a different error that you may not be expecting:

shell> mysql --host --user jon
ERROR 2005 (HY000): Unknown MySQL server host '--user' (1)

Because mysql assumes that any string following --host on the command line is a host name, --host --user is interpreted as --host=--user, and the client attempts to connect to a MySQL server running on a host named “--user”.

Options having default values always require an equals sign when assigning a value; failing to do so causes an error. For example, the MySQL server --log-error option has the default value host_name.err, where host_name is the name of the host on which MySQL is running. Assume that you are running MySQL on a computer whose host name is “tonfisk”, and consider the following invocation of mysqld_safe:

shell> mysqld_safe &
[1] 11699
shell> 080112 12:53:40 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
080112 12:53:40 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
shell>

After shutting down the server, restart it as follows:

shell> mysqld_safe --log-error &
[1] 11699
shell> 080112 12:53:40 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
080112 12:53:40 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
shell>

The result is the same, since --log-error is not followed by anything else on the command line, and it supplies its own default value. (The & character tells the operating system to run MySQL in the background; it is ignored by MySQL itself.) Now suppose that you wish to log errors to a file named my-errors.err. You might try starting the server with --log-error my-errors, but this does not have the intended effect, as shown here:

shell> mysqld_safe --log-error my-errors &
[1] 31357
shell> 080111 22:53:31 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
080111 22:53:32 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var
080111 22:53:34 mysqld_safe mysqld from pid file /usr/local/mysql/var/tonfisk.pid ended

[1]+  Done                    ./mysqld_safe --log-error my-errors

The server attempted to start using /usr/local/mysql/var/tonfisk.err as the error log, but then shut down. Examining the last few lines of this file shows the reason:

shell> tail /usr/local/mysql/var/tonfisk.err
080111 22:53:32  InnoDB: Started; log sequence number 0 46409
/usr/local/mysql/libexec/mysqld: Too many arguments (first extra is 'my-errors').
Use --verbose --help to get a list of available options
080111 22:53:32 [ERROR] Aborting

080111 22:53:32  InnoDB: Starting shutdown...
080111 22:53:34  InnoDB: Shutdown completed; log sequence number 0 46409
080111 22:53:34 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete

080111 22:53:34 mysqld_safe mysqld from pid file /usr/local/mysql/var/tonfisk.pid ended

Because the --log-error option supplies a default value, you must use an equals sign to assign a different value to it, as shown here:

shell> mysqld_safe --log-error=my-errors &
[1] 31437
shell> 080111 22:54:15 mysqld_safe Logging to '/usr/local/mysql/var/my-errors.err'.
080111 22:54:15 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/var

shell>

Now the server has been started successfully, and is logging errors to the file /usr/local/mysql/var/my-errors.err.

Similar issues can arise when specifying option values in option files. For example, consider a my.cnf file that contains the following:

[mysql]

host
user

When the mysql client reads this file, these entries are parsed as --host --user or --host=--user, with the result shown here:

shell> mysql
ERROR 2005 (HY000): Unknown MySQL server host '--user' (1)

However, in option files, an equals sign is not assumed. Suppose the my.cnf file is as shown here:

[mysql]

user jon

Trying to start mysql in this case causes a different error:

shell> mysql
mysql: unknown option '--user jon'

A similar error would occur if you were to write host tonfisk in the option file rather than host=tonfisk. Instead, you must use the equals sign:

[mysql]

user=jon

shell> mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 6.0.12 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> SELECT USER();
+---------------+
| USER()        |
+---------------+
| jon@localhost |
+---------------+
1 row in set (0.00 sec)

This is not the same behavior as with the command line, where the equals sign is not required:

shell> mysql --user jon --host tonfisk
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 6.0.12 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> SELECT USER();
+---------------+
| USER()        |
+---------------+
| jon@tonfisk   |
+---------------+
1 row in set (0.00 sec)

Beginning with MySQL 6.0.12, specifying an option requiring a value without a value in an option file causes the server to abort with an error. For example, suppose my.cnf contains the following:

[mysqld]
log_error
relay_log
relay_log_index

This causes the server to fail on startup, as shown here:

shell> mysqld_safe &

090514 09:48:39 mysqld_safe Logging to '/home/jon/bin/mysql-6.0/var/tonfisk.err'.
090514 09:48:39 mysqld_safe Starting mysqld daemon with databases from /home/jon/bin/mysql-6.0/var
090514 09:48:39 mysqld_safe mysqld from pid file /home/jon/bin/mysql-6.0/var/tonfisk.pid ended

The --log-error option does not require an argument; however, the --relay-log option requires one, as shown in the error log (which in the absence of a specified value, defaults to datadir/hostname.err):

shell> tail -n 3 ../var/tonfisk.err

090514 09:48:39 mysqld_safe Starting mysqld daemon with databases from /home/jon/bin/mysql-6.0/var
090514  9:48:39 [ERROR] /home/jon/bin/mysql-6.0/libexec/mysqld: option '--relay-log' requires an argument
090514  9:48:39 [ERROR] Aborting

This is a change from previous behavior, where the server would have interpreted the last two lines in the example my.cnf file as --relay-log=relay_log_index and created a relay log file using “relay_log_index” as the basename. (Bug#25192)

4.2.4. Setting Environment Variables

Environment variables can be set at the command prompt to affect the current invocation of your command processor, or set permanently to affect future invocations. To set a variable permanently, you can set it in a startup file or by using the interface provided by your system for this purpose. Consult the documentation for your command interpreter for specific details. Section 2.13, “Environment Variables”, lists all environment variables that affect MySQL program operation.

To specify a value for an environment variable, use the syntax appropriate for your command processor. For example, on Windows or NetWare, you can set the USER variable to specify your MySQL account name. To do so, use this syntax:

SET USER=your_name

The syntax on Unix depends on your shell. Suppose that you want to specify the TCP/IP port number using the MYSQL_TCP_PORT variable. Typical syntax (such as for sh, bash, zsh, and so on) is as follows:

MYSQL_TCP_PORT=3306
export MYSQL_TCP_PORT

The first command sets the variable, and the export command exports the variable to the shell environment so that its value becomes accessible to MySQL and other processes.

For csh and tcsh, use setenv to make the shell variable available to the environment:

setenv MYSQL_TCP_PORT 3306

The commands to set environment variables can be executed at your command prompt to take effect immediately, but the settings persist only until you log out. To have the settings take effect each time you log in, use the interface provided by your system or place the appropriate command or commands in a startup file that your command interpreter reads each time it starts.

On Windows, you can set environment variables using the System Control Panel (under Advanced).

On Unix, typical shell startup files are .bashrc or .bash_profile for bash, or .tcshrc for tcsh.

Suppose that your MySQL programs are installed in /usr/local/mysql/bin and that you want to make it easy to invoke these programs. To do this, set the value of the PATH environment variable to include that directory. For example, if your shell is bash, add the following line to your .bashrc file:

PATH=${PATH}:/usr/local/mysql/bin

bash uses different startup files for login and nonlogin shells, so you might want to add the setting to .bashrc for login shells and to .bash_profile for nonlogin shells to make sure that PATH is set regardless.

If your shell is tcsh, add the following line to your .tcshrc file:

setenv PATH ${PATH}:/usr/local/mysql/bin

If the appropriate startup file does not exist in your home directory, create it with a text editor.

After modifying your PATH setting, open a new console window on Windows or log in again on Unix so that the setting goes into effect.

4.3. MySQL Server and Server-Startup Programs

This section describes mysqld, the MySQL server, and several programs that are used to start the server.

4.3.1. mysqld — The MySQL Server

mysqld, also known as MySQL Server, is the main program that does most of the work in a MySQL installation. MySQL Server manages access to the MySQL data directory that contains databases and tables. The data directory is also the default location for other information such as log files and status files.

When MySQL server starts, it listens for network connections from client programs and manages access to databases on behalf of those clients.

The mysqld program has many options that can be specified at startup. For a complete list of options, run this command:

shell> mysqld --verbose --help

MySQL Server also has a set of system variables that affect its operation as it runs. System variables can be set at server startup, and many of them can be changed at runtime to effect dynamic server reconfiguration. MySQL Server also has a set of status variables that provide information about its operation. You can monitor these status variables to access runtime performance characteristics.

For a full description of MySQL Server command options, system variables, and status variables, see Section 5.1, “The MySQL Server”. For information about installing MySQL and setting up the initial configuration, see Chapter 2, Installing and Upgrading MySQL.

4.3.2. mysqld_safe — MySQL Server Startup Script

mysqld_safe is the recommended way to start a mysqld server on Unix and NetWare. mysqld_safe adds some safety features such as restarting the server when an error occurs and logging runtime information to an error log file. Descriptions of error logging and NetWare-specific behaviors are given later in this section.

mysqld_safe tries to start an executable named mysqld. To override the default behavior and specify explicitly the name of the server you want to run, specify a --mysqld or --mysqld-version option to mysqld_safe. You can also use --ledir to indicate the directory where mysqld_safe should look for the server.

Many of the options to mysqld_safe are the same as the options to mysqld. See Section 5.1.2, “Server Command Options”.

Options unknown to mysqld_safe are passed to mysqld if they are specified on the command line, but ignored if they are specified in the [mysqld_safe] group of an option file. See Section 4.2.3.3, “Using Option Files”.

mysqld_safe reads all options from the [mysqld], [server], and [mysqld_safe] sections in option files. For example, if you specify a [mysqld] section like this, mysqld_safe will find and use the --log-error option:

[mysqld]
log-error=error.log

For backward compatibility, mysqld_safe also reads [safe_mysqld] sections, although you should rename such sections to [mysqld_safe] in MySQL 6.0 installations.

Table 4.1. mysqld_safe Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--autocloseautocloseOn NetWare, mysqld_safe provides a screen presence   
--basedir=pathbasedirThe path to the MySQL installation directory   
--core-file-size=sizecore-file-sizeThe size of the core file that mysqld should be able to create   
--datadir=pathdatadirThe path to the data directory   
--defaults-extra-file=pathdefaults-extra-fileThe name of an option file to be read in addition to the usual option files   
--defaults-file=file_namedefaults-fileThe name of an option file to be read instead of the usual option files   
--help Display a help message and exit   
--ledir=pathledirUse this option to indicate the path name to the directory where the server is located   
--log-error=file_namelog-errorWrite the error log to the given file   
--mysqld=prog_namemysqldThe name of the server program (in the ledir directory) that you want to start   
--mysqld-version=suffixmysqld-versionThis option is similar to the --mysqld option, but you specify only the suffix for the server program name   
--nice=priorityniceUse the nice program to set the server's scheduling priority to the given value   
--no-defaultsno-defaultsDo not read any option files   
--open-files-limit=countopen-files-limitThe number of files that mysqld should be able to open   
--pid-filepid-fileThe path name of the process ID file   
--port=numberportThe port number that the server should use when listening for TCP/IP connections   
--skip-kill-mysqldskip-kill-mysqldDo not try to kill stray mysqld processes   
--skip-syslogskip-syslogDo not write error messages to syslog; use error log file   
--socket=pathsocketThe Unix socket file that the server should use when listening for local connections   
--syslogsyslogWrite error messages to syslog   
--timezone=timezonetimezoneSet the TZ time zone environment variable to the given option value   
--user={user_name|user_id}userRun the mysqld server as the user having the name user_name or the numeric user ID user_id   

mysqld_safe supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help

    Display a help message and exit.

  • --autoclose

    (NetWare only) On NetWare, mysqld_safe provides a screen presence. When you unload (shut down) the mysqld_safe NLM, the screen does not by default go away. Instead, it prompts for user input:

    *<NLM has terminated; Press any key to close the screen>*
    

    If you want NetWare to close the screen automatically instead, use the --autoclose option to mysqld_safe.

  • --basedir=path

    The path to the MySQL installation directory.

  • --core-file-size=size

    The size of the core file that mysqld should be able to create. The option value is passed to ulimit -c.

  • --datadir=path

    The path to the data directory.

  • --defaults-extra-file=path

    The name of an option file to be read in addition to the usual option files. This must be the first option on the command line if it is used. If the file does not exist or is otherwise inaccessible, the server will exit with an error.

  • --defaults-file=file_name

    The name of an option file to be read instead of the usual option files. This must be the first option on the command line if it is used.

  • --ledir=path

    If mysqld_safe cannot find the server, use this option to indicate the path name to the directory where the server is located.

  • --log-error=file_name

    Write the error log to the given file. See Section 5.2.2, “The Error Log”.

  • --mysqld=prog_name

    The name of the server program (in the ledir directory) that you want to start. This option is needed if you use the MySQL binary distribution but have the data directory outside of the binary distribution. If mysqld_safe cannot find the server, use the --ledir option to indicate the path name to the directory where the server is located.

  • --mysqld-version=suffix

    This option is similar to the --mysqld option, but you specify only the suffix for the server program name. The basename is assumed to be mysqld. For example, if you use --mysqld-version=debug, mysqld_safe starts the mysqld-debug program in the ledir directory. If the argument to --mysqld-version is empty, mysqld_safe uses mysqld in the ledir directory.

  • --nice=priority

    Use the nice program to set the server's scheduling priority to the given value.

  • --no-defaults

    Do not read any option files. This must be the first option on the command line if it is used.

  • --open-files-limit=count

    The number of files that mysqld should be able to open. The option value is passed to ulimit -n. Note that you need to start mysqld_safe as root for this to work properly!

  • --pid-file=file_name

    The path name of the process ID file.

  • --port=port_num

    The port number that the server should use when listening for TCP/IP connections. The port number must be 1024 or higher unless the server is started by the root system user.

  • --skip-kill-mysqld

    Do not try to kill stray mysqld processes at startup. This option works only on Linux.

  • --socket=path

    The Unix socket file that the server should use when listening for local connections.

  • --syslog, --skip-syslog

    --syslog causes error messages to be sent to syslog on systems that support the logger program. --skip-syslog suppresses the use of syslog; messages are written to an error log file.

  • --syslog-tag=tag

    For logging to syslog, messages from mysqld_safe and mysqld are written with a tag of mysqld_safe and mysqld, respectively. To specify a suffix for the tag, use --syslog-tag=tag, which modifies the tags to be mysqld_safe-tag and mysqld-tag.

  • --timezone=timezone

    Set the TZ time zone environment variable to the given option value. Consult your operating system documentation for legal time zone specification formats.

  • --user={user_name|user_id}

    Run the mysqld server as the user having the name user_name or the numeric user ID user_id. (“User” in this context refers to a system login account, not a MySQL user listed in the grant tables.)

If you execute mysqld_safe with the --defaults-file or --defaults-extra-file option to name an option file, the option must be the first one given on the command line or the option file will not be used. For example, this command will not use the named option file:

mysql> mysqld_safe --port=port_num --defaults-file=file_name

Instead, use the following command:

mysql> mysqld_safe --defaults-file=file_name --port=port_num

The mysqld_safe script is written so that it normally can start a server that was installed from either a source or a binary distribution of MySQL, even though these types of distributions typically install the server in slightly different locations. (See Section 2.1.5, “Installation Layouts”.) mysqld_safe expects one of the following conditions to be true:

  • The server and databases can be found relative to the working directory (the directory from which mysqld_safe is invoked). For binary distributions, mysqld_safe looks under its working directory for bin and data directories. For source distributions, it looks for libexec and var directories. This condition should be met if you execute mysqld_safe from your MySQL installation directory (for example, /usr/local/mysql for a binary distribution).

  • If the server and databases cannot be found relative to the working directory, mysqld_safe attempts to locate them by absolute path names. Typical locations are /usr/local/libexec and /usr/local/var. The actual locations are determined from the values configured into the distribution at the time it was built. They should be correct if MySQL is installed in the location specified at configuration time.

Because mysqld_safe tries to find the server and databases relative to its own working directory, you can install a binary distribution of MySQL anywhere, as long as you run mysqld_safe from the MySQL installation directory:

shell> cd mysql_installation_directory
shell> bin/mysqld_safe &

If mysqld_safe fails, even when invoked from the MySQL installation directory, you can specify the --ledir and --datadir options to indicate the directories in which the server and databases are located on your system.

When you use mysqld_safe to start mysqld, mysqld_safe arranges for error (and notice) messages from itself and from mysqld to go to the same destination.

There are several mysqld_safe options for controlling the destination of these messages:

  • --syslog: Write error messages to syslog on systems that support the logger program.

  • --skip-syslog: Do not write error messages to syslog. Messages are written to the default error log file (host_name.err in the data directory), or to a named file if the --log-error option is given.

  • --log-error=file_name: Write error messages to the named error file.

If none of these options is given, the default is --skip-syslog.

If --syslog and --log-error are both given, a warning is issued and --log-error takes precedence.

When mysqld_safe writes a message, notices go to the logging destination (syslog or the error log file) and stdout. Errors go to the logging destination and stderr.

Normally, you should not edit the mysqld_safe script. Instead, configure mysqld_safe by using command-line options or options in the [mysqld_safe] section of a my.cnf option file. In rare cases, it might be necessary to edit mysqld_safe to get it to start the server properly. However, if you do this, your modified version of mysqld_safe might be overwritten if you upgrade MySQL in the future, so you should make a copy of your edited version that you can reinstall.

On NetWare, mysqld_safe is a NetWare Loadable Module (NLM) that is ported from the original Unix shell script. It starts the server as follows:

  1. Runs a number of system and option checks.

  2. Runs a check on MyISAM tables.

  3. Provides a screen presence for the MySQL server.

  4. Starts mysqld, monitors it, and restarts it if it terminates in error.

  5. Sends error messages from mysqld to the host_name.err file in the data directory.

  6. Sends mysqld_safe screen output to the host_name.safe file in the data directory.

4.3.3. mysql.server — MySQL Server Startup Script

MySQL distributions on Unix include a script named mysql.server. It can be used on systems such as Linux and Solaris that use System V-style run directories to start and stop system services. It is also used by the Mac OS X Startup Item for MySQL.

mysql.server can be found in the support-files directory under your MySQL installation directory or in a MySQL source distribution.

If you use the Linux server RPM package (MySQL-server-VERSION.rpm), the mysql.server script will be installed in the /etc/init.d directory with the name mysql. You need not install it manually. See Section 2.4, “Installing MySQL from RPM Packages on Linux”, for more information on the Linux RPM packages.

Some vendors provide RPM packages that install a startup script under a different name such as mysqld.

If you install MySQL from a source distribution or using a binary distribution format that does not install mysql.server automatically, you can install it manually. Instructions are provided in Section 2.10.2.2, “Starting and Stopping MySQL Automatically”.

mysql.server reads options from the [mysql.server] and [mysqld] sections of option files. For backward compatibility, it also reads [mysql_server] sections, although you should rename such sections to [mysql.server] when using MySQL 6.0.

mysql.server supports the following options:

4.3.4. mysqld_multi — Manage Multiple MySQL Servers

mysqld_multi is designed to manage several mysqld processes that listen for connections on different Unix socket files and TCP/IP ports. It can start or stop servers, or report their current status.

mysqld_multi searches for groups named [mysqldN] in my.cnf (or in the file named by the --config-file option). N can be any positive integer. This number is referred to in the following discussion as the option group number, or GNR. Group numbers distinguish option groups from one another and are used as arguments to mysqld_multi to specify which servers you want to start, stop, or obtain a status report for. Options listed in these groups are the same that you would use in the [mysqld] group used for starting mysqld. (See, for example, Section 2.10.2.2, “Starting and Stopping MySQL Automatically”.) However, when using multiple servers, it is necessary that each one use its own value for options such as the Unix socket file and TCP/IP port number. For more information on which options must be unique per server in a multiple-server environment, see Section 5.6, “Running Multiple MySQL Servers on the Same Machine”.

To invoke mysqld_multi, use the following syntax:

shell> mysqld_multi [options] {start|stop|report} [GNR[,GNR] ...]

start, stop, and report indicate which operation to perform. You can perform the designated operation for a single server or multiple servers, depending on the GNR list that follows the option name. If there is no list, mysqld_multi performs the operation for all servers in the option file.

Each GNR value represents an option group number or range of group numbers. The value should be the number at the end of the group name in the option file. For example, the GNR for a group named [mysqld17] is 17. To specify a range of numbers, separate the first and last numbers by a dash. The GNR value 10-13 represents groups [mysqld10] through [mysqld13]. Multiple groups or group ranges can be specified on the command line, separated by commas. There must be no whitespace characters (spaces or tabs) in the GNR list; anything after a whitespace character is ignored.

This command starts a single server using option group [mysqld17]:

shell> mysqld_multi start 17

This command stops several servers, using option groups [mysqld8] and [mysqld10] through [mysqld13]:

shell> mysqld_multi stop 8,10-13

For an example of how you might set up an option file, use this command:

shell> mysqld_multi --example

mysqld_multi searches for option files as follows:

Option files read are searched for [mysqld_multi] and [mysqldN] option groups.

mysqld_multi supports the following options:

  • --help

    Display a help message and exit.

  • --config-file=file_name

    This option is deprecated. If given, it is treated the same way as --defaults-extra-file, described earlier.

  • --example

    Display a sample option file.

  • --log=file_name

    Specify the name of the log file. If the file exists, log output is appended to it.

  • --mysqladmin=prog_name

    The mysqladmin binary to be used to stop servers.

  • --mysqld=prog_name

    The mysqld binary to be used. Note that you can specify mysqld_safe as the value for this option also. If you use mysqld_safe to start the server, you can include the mysqld or ledir options in the corresponding [mysqldN] option group. These options indicate the name of the server that mysqld_safe should start and the path name of the directory where the server is located. (See the descriptions for these options in Section 4.3.2, “mysqld_safe — MySQL Server Startup Script”.) Example:

    [mysqld38]
    mysqld = mysqld-debug
    ledir  = /opt/local/mysql/libexec
    
  • --no-log

    Print log information to stdout rather than to the log file. By default, output goes to the log file.

  • --password=password

    The password of the MySQL account to use when invoking mysqladmin. Note that the password value is not optional for this option, unlike for other MySQL programs.

  • --silent

    Silent mode; disable warnings.

  • --tcp-ip

    Connect to each MySQL server via the TCP/IP port instead of the Unix socket file. (If a socket file is missing, the server might still be running, but accessible only via the TCP/IP port.) By default, connections are made using the Unix socket file. This option affects stop and report operations.

  • --user=user_name

    The user name of the MySQL account to use when invoking mysqladmin.

  • --verbose

    Be more verbose.

  • --version

    Display version information and exit.

Some notes about mysqld_multi:

  • Most important: Before using mysqld_multi be sure that you understand the meanings of the options that are passed to the mysqld servers and why you would want to have separate mysqld processes. Beware of the dangers of using multiple mysqld servers with the same data directory. Use separate data directories, unless you know what you are doing. Starting multiple servers with the same data directory does not give you extra performance in a threaded system. See Section 5.6, “Running Multiple MySQL Servers on the Same Machine”.

  • Important

    Make sure that the data directory for each server is fully accessible to the Unix account that the specific mysqld process is started as. Do not use the Unix root account for this, unless you know what you are doing. See Section 5.3.5, “How to Run MySQL as a Normal User”.

  • Make sure that the MySQL account used for stopping the mysqld servers (with the mysqladmin program) has the same user name and password for each server. Also, make sure that the account has the SHUTDOWN privilege. If the servers that you want to manage have different user names or passwords for the administrative accounts, you might want to create an account on each server that has the same user name and password. For example, you might set up a common multi_admin account by executing the following commands for each server:

    shell> mysql -u root -S /tmp/mysql.sock -p
    Enter password:
    mysql> GRANT SHUTDOWN ON *.*
        -> TO 'multi_admin'@'localhost' IDENTIFIED BY 'multipass';
    

    See Section 5.4, “The MySQL Access Privilege System”. You have to do this for each mysqld server. Change the connection parameters appropriately when connecting to each one. Note that the host name part of the account name must allow you to connect as multi_admin from the host where you want to run mysqld_multi.

  • The Unix socket file and the TCP/IP port number must be different for every mysqld. (Alternatively, if the host has multiple network addresses, you can use --bind-address to cause different servers to listen to different interfaces.)

  • The --pid-file option is very important if you are using mysqld_safe to start mysqld (for example, --mysqld=mysqld_safe) Every mysqld should have its own process ID file. The advantage of using mysqld_safe instead of mysqld is that mysqld_safe monitors its mysqld process and restarts it if the process terminates due to a signal sent using kill -9 or for other reasons, such as a segmentation fault. Please note that the mysqld_safe script might require that you start it from a certain place. This means that you might have to change location to a certain directory before running mysqld_multi. If you have problems starting, please see the mysqld_safe script. Check especially the lines:

    ----------------------------------------------------------------
    MY_PWD=`pwd`
    # Check if we are starting this relative (for the binary release)
    if test -d $MY_PWD/data/mysql -a \
       -f ./share/mysql/english/errmsg.sys -a \
       -x ./bin/mysqld
    ----------------------------------------------------------------
    

    The test performed by these lines should be successful, or you might encounter problems. See Section 4.3.2, “mysqld_safe — MySQL Server Startup Script”.

  • You might want to use the --user option for mysqld, but to do this you need to run the mysqld_multi script as the Unix root user. Having the option in the option file doesn't matter; you just get a warning if you are not the superuser and the mysqld processes are started under your own Unix account.

The following example shows how you might set up an option file for use with mysqld_multi. The order in which the mysqld programs are started or stopped depends on the order in which they appear in the option file. Group numbers need not form an unbroken sequence. The first and fifth [mysqldN] groups were intentionally omitted from the example to illustrate that you can have “gaps” in the option file. This gives you more flexibility.

# This file should probably be in your home dir (~/.my.cnf)
# or /etc/my.cnf
# Version 2.1 by Jani Tolonen

[mysqld_multi]
mysqld     = /usr/local/bin/mysqld_safe
mysqladmin = /usr/local/bin/mysqladmin
user       = multi_admin
password   = multipass

[mysqld2]
socket     = /tmp/mysql.sock2
port       = 3307
pid-file   = /usr/local/mysql/var2/hostname.pid2
datadir    = /usr/local/mysql/var2
language   = /usr/local/share/mysql/english
user       = john

[mysqld3]
socket     = /tmp/mysql.sock3
port       = 3308
pid-file   = /usr/local/mysql/var3/hostname.pid3
datadir    = /usr/local/mysql/var3
language   = /usr/local/share/mysql/swedish
user       = monty

[mysqld4]
socket     = /tmp/mysql.sock4
port       = 3309
pid-file   = /usr/local/mysql/var4/hostname.pid4
datadir    = /usr/local/mysql/var4
language   = /usr/local/share/mysql/estonia
user       = tonu

[mysqld6]
socket     = /tmp/mysql.sock6
port       = 3311
pid-file   = /usr/local/mysql/var6/hostname.pid6
datadir    = /usr/local/mysql/var6
language   = /usr/local/share/mysql/japanese
user       = jani

See Section 4.2.3.3, “Using Option Files”.

4.4. MySQL Installation-Related Programs

The programs in this section are used when installing or upgrading MySQL.

4.4.1. comp_err — Compile MySQL Error Message File

comp_err creates the errmsg.sys file that is used by mysqld to determine the error messages to display for different error codes. comp_err normally is run automatically when MySQL is built. It compiles the errmsg.sys file from the plaintext file located at sql/share/errmsg.txt in MySQL source distributions.

comp_err also generates mysqld_error.h, mysqld_ername.h, and sql_state.h header files.

For more information about how error messages are defined, see the MySQL Internals Manual.

Invoke comp_err like this:

shell> comp_err [options]

comp_err supports the options described in the following list.

4.4.2. make_win_bin_dist — Package MySQL Distribution as ZIP Archive

This script is used on Windows after building a MySQL distribution from source to create executable programs. It packages the binaries and support files into a ZIP archive that can be unpacked at the location where you want to install MySQL.

make_win_bin_dist is a shell script, so you must have Cygwin installed to use it.

This program's use is subject to change. Currently, you invoke it as follows from the root directory of your source distribution:

shell> make_win_bin_dist [options] package_basename [copy_def ...]

The package_basename argument provides the basename for the resulting ZIP archive. This name will be the name of the directory that results from unpacking the archive.

Because you might want to include files of directories from other builds, you can instruct this script do copy them in for you, via copy_def arguments, which of which is of the form relative_dest_name=source_name.

Example:

bin/mysqld-max.exe=../my-max-build/sql/release/mysqld.exe

If you specify a directory, the entire directory will be copied.

make_win_bin_dist supports the following options:

  • --debug

    Pack the debug binaries and produce an error if they were not built.

  • --embedded

    Pack the embedded server and produce an error if it was not built. The default is to pack it if it was built.

  • --exe-suffix=suffix

    Add a suffix to the basename of the mysql binary. For example, a suffix of -abc produces a binary named mysqld-abc.exe.

  • --no-debug

    Do not pack the debug binaries even if they were built.

  • --no-embedded

    Do not pack the embedded server even if it was built.

  • --only-debug

    Use this option when the target for this build was Debug, and you just want to replace the normal binaries with debug versions (that is, do not use separate debug directories).

4.4.3. mysqlbug — Generate Bug Report

This program enables you to generate a bug report and send it to Sun Microsystems, Inc. It is a shell script and runs on Unix.

The normal way to report bugs is to visit http://bugs.mysql.com/, which is the address for our bugs database. This database is public and can be browsed and searched by anyone. If you log in to the system, you can enter new reports. If you have no Web access, you can generate a bug report by using the mysqlbug script.

mysqlbug helps you generate a report by determining much of the following information automatically, but if something important is missing, please include it with your message. mysqlbug can be found in the scripts directory (source distribution) and in the bin directory under your MySQL installation directory (binary distribution).

Invoke mysqlbug without arguments:

shell> mysqlbug

The script will place you in an editor with a copy of the report to be sent. Edit the lines near the beginning that indicate the nature of the problem. Then write the file to save your changes, quit the editor, and mysqlbug will send the report by email.

4.4.4. mysql_fix_privilege_tables — Upgrade MySQL System Tables

Note

In MySQL 5.1.7, mysql_fix_privilege_tables was superseded by mysql_upgrade, which should be used instead. See Section 4.4.8, “mysql_upgrade — Check Tables for MySQL Upgrade”. In MySQL 6.0.11, mysql_fix_privilege_tables was removed.

Some releases of MySQL introduce changes to the structure of the system tables in the mysql database to add new privileges or support new features. When you update to a new version of MySQL, you should update your system tables as well to make sure that their structure is up to date. Otherwise, there might be capabilities that you cannot take advantage of.

mysql_fix_privilege_tables is an older script that previously was used to uprade the system tables in the mysql database after a MySQL upgrade.

Before running mysql_fix_privilege_tables, make a backup of your mysql database.

On Unix or Unix-like systems, update the system tables by running the mysql_fix_privilege_tables script:

shell> mysql_fix_privilege_tables

You must run this script while the server is running. It attempts to connect to the server running on the local host as root. If your root account requires a password, indicate the password on the command line like this:

shell> mysql_fix_privilege_tables --password=root_password

The mysql_fix_privilege_tables script performs any actions necessary to convert your system tables to the current format. You might see some Duplicate column name warnings as it runs; you can ignore them.

After running the script, stop the server and restart it so that any changes made to the system tables take effect.

On Windows systems, MySQL distributions include a mysql_fix_privilege_tables.sql SQL script that you can run using the mysql client. For example, if your MySQL installation is located at C:\Program Files\MySQL\MySQL Server 6.0, the commands look like this:

C:\> cd "C:\Program Files\MySQL\MySQL Server 6.0"
C:\> bin\mysql -u root -p mysql
mysql> SOURCE scripts/mysql_fix_privilege_tables.sql

The mysql command will prompt you for the root password; enter it when prompted.

If your installation is located in some other directory, adjust the path names appropriately.

As with the Unix procedure, you might see some Duplicate column name warnings as mysql processes the statements in the mysql_fix_privilege_tables.sql script; you can ignore them.

After running the script, stop the server and restart it.

4.4.5. mysql_install_db — Initialize MySQL Data Directory

mysql_install_db initializes the MySQL data directory and creates the system tables that it contains, if they do not exist.

To invoke mysql_install_db, use the following syntax:

shell> mysql_install_db [options]

Because the MySQL server, mysqld, needs to access the data directory when it runs later, you should either run mysql_install_db from the same account that will be used for running mysqld or run it as root and use the --user option to indicate the user name that mysqld will run as. It might be necessary to specify other options such as --basedir or --datadir if mysql_install_db does not use the correct locations for the installation directory or data directory. For example:

shell> bin/mysql_install_db --user=mysql \
         --basedir=/opt/mysql/mysql \
         --datadir=/opt/mysql/mysql/data

mysql_install_db needs to invoke mysqld with the --bootstrap and --skip-grant-tables options (see Section 2.9.2, “Typical configure Options”). If MySQL was configured with the --disable-grant-options option, --bootstrap and --skip-grant-tables will be disabled. To handle this, set the MYSQLD_BOOTSTRAP environment variable to the full path name of a server that has all options enabled. mysql_install_db will use that server.

mysql_install_db supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --basedir=path

    The path to the MySQL installation directory.

  • --force

    Cause mysql_install_db to run even if DNS does not work. In that case, grant table entries that normally use host names will use IP addresses.

  • --datadir=path, --ldata=path

    The path to the MySQL data directory.

  • --rpm

    For internal use. This option is used by RPM files during the MySQL installation process.

  • --skip-name-resolve

    Use IP addresses rather than host names when creating grant table entries. This option can be useful if your DNS does not work.

  • --srcdir=path

    For internal use. The directory under which mysql_install_db looks for support files such as the error message file and the file for populating the help tables. This option was added in MySQL 5.1.14.

  • --user=user_name

    The login user name to use for running mysqld. Files and directories created by mysqld will be owned by this user. You must be root to use this option. By default, mysqld runs using your current login name and files and directories that it creates will be owned by you.

  • --verbose

    Verbose mode. Print more information about what the program does.

  • --windows

    For internal use. This option is used for creating Windows distributions.

4.4.6. mysql_secure_installation — Improve MySQL Installation Security

This program enables you to improve the security of your MySQL installation in the following ways:

  • You can set a password for root accounts.

  • You can remove root accounts that are accessible from outside the local host.

  • You can remove anonymous-user accounts.

  • You can remove the test database, which by default can be accessed by anonymous users.

Invoke mysql_secure_installation without arguments:

shell> mysql_secure_installation

The script will prompt you to determine which actions to perform.

4.4.7. mysql_tzinfo_to_sql — Load the Time Zone Tables

The mysql_tzinfo_to_sql program loads the time zone tables in the mysql database. It is used on systems that have a zoneinfo database (the set of files describing time zones). Examples of such systems are Linux, FreeBSD, Sun Solaris, and Mac OS X. One likely location for these files is the /usr/share/zoneinfo directory (/usr/share/lib/zoneinfo on Solaris). If your system does not have a zoneinfo database, you can use the downloadable package described in Section 9.7, “MySQL Server Time Zone Support”.

mysql_tzinfo_to_sql can be invoked several ways:

shell> mysql_tzinfo_to_sql tz_dir
shell> mysql_tzinfo_to_sql tz_file tz_name
shell> mysql_tzinfo_to_sql --leap tz_file

For the first invocation syntax, pass the zoneinfo directory path name to mysql_tzinfo_to_sql and send the output into the mysql program. For example:

shell> mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql

mysql_tzinfo_to_sql reads your system's time zone files and generates SQL statements from them. mysql processes those statements to load the time zone tables.

The second syntax causes mysql_tzinfo_to_sql to load a single time zone file tz_file that corresponds to a time zone name tz_name:

shell> mysql_tzinfo_to_sql tz_file tz_name | mysql -u root mysql

If your time zone needs to account for leap seconds, invoke mysql_tzinfo_to_sql using the third syntax, which initializes the leap second information. tz_file is the name of your time zone file:

shell> mysql_tzinfo_to_sql --leap tz_file | mysql -u root mysql

After running mysql_tzinfo_to_sql, it is best to restart the server so that it does not continue to use any previously cached time zone data.

4.4.8. mysql_upgrade — Check Tables for MySQL Upgrade

mysql_upgrade examines all tables in all databases for incompatibilities with the current version of MySQL Server. mysql_upgrade also upgrades the system tables so that you can take advantage of new privileges or capabilities that might have been added.

mysql_upgrade should be executed each time you upgrade MySQL. It supersedes the older mysql_fix_privilege_tables script, which has been removed in MySQL 6.0.

If a table is found to have a possible incompatibility, mysql_upgrade performs a table check. If any problems are found, a table repair is attempted. If the table cannot be repaired, see Section 2.11.4, “Rebuilding or Repairing Tables or Indexes” for manual table repair strategies.

Caution

You should always back up your current MySQL installation before performing an upgrade. See Section 6.1, “Database Backups”.

Some upgrade incompatibilities may require special handling before you upgrade your MySQL installation and run mysql_upgrade. See Section 2.11.1, “Upgrading MySQL”, for instructions on determining whether any such incompatibilities apply to your installation and how to handle them.

To use mysql_upgrade, make sure that the server is running, and then invoke it like this:

shell> mysql_upgrade [options]

After running mysql_upgrade, stop the server and restart it so that any changes made to the system tables take effect.

mysql_upgrade executes the following commands to check and repair tables and to upgrade the system tables:

mysqlcheck --all-databases --check-upgrade --auto-repair
mysql < fix_priv_tables
mysqlcheck --all-databases --check-upgrade --fix-db-names --fix-table-names

Notes about the preceding commands:

All checked and repaired tables are marked with the current MySQL version number. This ensures that next time you run mysql_upgrade with the same version of the server, it can tell whether there is any need to check or repair the table again.

mysql_upgrade also saves the MySQL version number in a file named mysql_upgrade_info in the data directory. This is used to quickly check whether all tables have been checked for this release so that table-checking can be skipped. To ignore this file and perform the check regardless, use the --force option.

If you install MySQL from RPM packages on Linux, you must install the server and client RPMs. mysql_upgrade is included in the server RPM but requires the client RPM because the latter includes mysqlcheck. (See Section 2.4, “Installing MySQL from RPM Packages on Linux”.)

mysql_upgrade supports the options in the following list. It also reads option files (the [mysql_upgrade] and [client] groups) and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”. Other options are passed to mysqlcheck. For example, it might be necessary to specify the --password[=password] option.

  • --help

    Display a short help message and exit.

  • --basedir=path

    The path to the MySQL installation directory.

  • --datadir=path

    The path to the data directory.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info, -T

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --force

    Ignore the mysql_upgrade_info file and force execution of mysqlcheck even if mysql_upgrade has already been executed for the current version of MySQL.

  • --tmpdir=path, -t path

    The path name of the directory to use for creating temporary files. This option was added in MySQL 6.0.6.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server. The default user name is root.

  • --verbose

    Verbose mode. Print more information about what the program does.

4.5. MySQL Client Programs

This section describes client programs that connect to the MySQL server.

4.5.1. mysql — The MySQL Command-Line Tool

mysql is a simple SQL shell (with GNU readline capabilities). It supports interactive and noninteractive use. When used interactively, query results are presented in an ASCII-table format. When used noninteractively (for example, as a filter), the result is presented in tab-separated format. The output format can be changed using command options.

If you have problems due to insufficient memory for large result sets, use the --quick option. This forces mysql to retrieve results from the server a row at a time rather than retrieving the entire result set and buffering it in memory before displaying it. This is done by returning the result set using the mysql_use_result() C API function in the client/server library rather than mysql_store_result().

Using mysql is very easy. Invoke it from the prompt of your command interpreter as follows:

shell> mysql db_name

Or:

shell> mysql --user=user_name --password=your_password db_name

Then type an SQL statement, end it with “;”, \g, or \G and press Enter.

Typing Control-C causes mysql to attempt to kill the current statement. If this cannot be done, or Control-C is typed again before the statement is killed, mysql exits. Previously, Control-C caused mysql to exit in all cases.

You can execute SQL statements in a script file (batch file) like this:

shell> mysql db_name < script.sql > output.tab

4.5.1.1. mysql Options

Table 4.2. mysql Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--auto-rehashauto-rehashEnable automatic rehashing   
--auto-vertical-outputauto-vertical-outputEnable automatic vertical result set display6.0.4  
--batchbatchDon't use history file   
--character-sets-dir=namecharacter-sets-dirSet the default character set   
--column-namescolumn-namesWrite column names in results   
--column-type-infocolumn-type-infoDisplay result set metadata   
--commentscommentsWhether to retain or strip comments in statements sent to the server6.0.4  
--compresscompressCompress all information sent between the client and the server   
--connect_timeout=valueconnect_timeoutThe number of seconds before connection timeout   
--database=dbnamedatabaseThe database to use   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--delimiter=strdelimiterSet the statement delimiter   
--execute=statementexecuteExecute the statement and quit   
--forceforceContinue even if an SQL error occurs   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--htmlhtmlProduce HTML output   
--ignore-spacesignore-spacesIgnore spaces after function names   
--line-numbersline-numbersWrite line numbers for errors   
--local-infile[={0|1}]local-infileEnable or disable for LOCAL capability for LOAD DATA INFILE   
--max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send to or receive from the server   
--max_join_size=valuemax_join_sizeThe automatic limit for rows in a join when using --safe-updates   
--named-commandsnamed-commandsEnable named mysql commands   
--net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and socket communication   
--no-auto-rehash Disable automatic rehashing   
--no-beepno-beepDo not beep when errors occur   
--no-named-commandsno-named-commandsDisable named mysql commands   
--no-pagerno-pagerDeprecated form of --skip-pager   
--no-teeno-teeDo not copy output to a file   
--one-databaseone-databaseIgnore statements except those for the default database named on the command line   
--pager[=command]pagerUse the given command for paging query output   
--password[=password]passwordThe password to use when connecting to the server   
--port=port_numportThe TCP/IP port number to use for the connection   
--prompt=format_strpromptSet the prompt to the specified format   
--protocol=typeprotocolThe connection protocol to use   
--quickquickDo not cache each query result   
--rawrawWrite column values without escape conversion   
--reconnectreconnectIf the connection to the server is lost, automatically try to reconnect   
--safe-updatessafe-updatesAllow only UPDATE and DELETE statements that specify key values   
--secure-authsecure-authDo not send passwords to the server in old (pre-4.1.1) format   
--select_limit=valueselect_limitThe automatic limit for SELECT statements when using --safe-updates   
--show-warningsshow-warningsShow warnings after each statement if there are any   
--sigint-ignoresigint-ignoreIgnore SIGINT signals (typically the result of typing Control-C)   
--silentsilentSilent mode   
--skip-auto-rehashskip-auto-rehashDisable automatic rehashing   
--skip-column-namesskip-column-namesDo not write column names in results   
--skip-line-numbersskip-line-numbersSkip line numbers for errors   
--skip-named-commandsskip-named-commandsDisable named mysql commands   
--skip-pagerskip-pagerDisable paging   
--skip-reconnectskip-reconnectDisable reconnecting   
--socket=pathsocketFor connections to localhost   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--tabletableDisplay output in tabular format   
--tee=file_nameteeAppend a copy of output to the given file   
--unbufferedunbufferedFlush the buffer after each query   
--user=user_nameuserThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   
--verticalverticalPrint query output rows vertically (one line per column value)   
--waitwaitIf the connection cannot be established, wait and retry instead of aborting   
--xmlxmlProduce XML output   

mysql supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help, -?

    Display a help message and exit.

  • --auto-rehash

    Enable automatic rehashing. This option is on by default, which enables database, table, and column name completion. Use --disable-auto-rehash to disable rehashing. That causes mysql to start faster, but you must issue the rehash command if you want to use name completion.

    To complete a name, enter the first part and press Tab. If the name is unambiguous, mysql completes it. Otherwise, you can press Tab again to see the possible names that begin with what you have typed so far. Completion does not occur if there is no default database.

  • --auto-vertical-output

    Cause result sets to be displayed vertically if they are too wide for the current window, and using normal tabular format otherwise. (This applies to statements terminated by ; or \G.) This option was added in MySQL 6.0.4.

  • --batch, -B

    Print results using tab as the column separator, with each row on a new line. With this option, mysql does not use the history file.

    Batch mode results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the --raw option.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --column-names

    Write column names in results.

  • --column-type-info, -m

    Display result set metadata.

  • --comments, -c

    Whether to preserve comments in statements sent to the server. The default is --skip-comments (discard comments), enable with --comments (preserve comments). This option was added in MySQL 6.0.4.

  • --compress, -C

    Compress all information sent between the client and the server if both support compression.

  • --database=db_name, -D db_name

    The database to use. This is useful primarily in an option file.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysql.trace'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info, -T

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --default-character-set=charset_name

    Use charset_name as the default character set. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --delimiter=str

    Set the statement delimiter. The default is the semicolon character (“;”).

  • --disable-named-commands

    Disable named commands. Use the \* form only, or use named commands only at the beginning of a line ending with a semicolon (“;”). mysql starts with this option enabled by default. However, even with this option, long-format commands still work from the first line. See Section 4.5.1.2, “mysql Commands”.

  • --execute=statement, -e statement

    Execute the statement and quit. The default output format is like that produced with --batch. See Section 4.2.3.1, “Using Options on the Command Line”, for some examples.

  • --force, -f

    Continue even if an SQL error occurs.

  • --host=host_name, -h host_name

    Connect to the MySQL server on the given host.

  • --html, -H

    Produce HTML output.

  • --ignore-spaces, -i

    Ignore spaces after function names. The effect of this is described in the discussion for the IGNORE_SPACE SQL mode (see Section 5.1.8, “Server SQL Modes”).

  • --line-numbers

    Write line numbers for errors. Disable this with --skip-line-numbers.

  • --local-infile[={0|1}]

    Enable or disable LOCAL capability for LOAD DATA INFILE. With no value, the option enables LOCAL. The option may be given as --local-infile=0 or --local-infile=1 to explicitly disable or enable LOCAL. Enabling LOCAL has no effect if the server does not also support it.

    MySQL Enterprise For expert advice on the security implications of enabling LOCAL, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • --named-commands, -G

    Enable named mysql commands. Long-format commands are allowed, not just short-format commands. For example, quit and \q both are recognized. Use --skip-named-commands to disable named commands. See Section 4.5.1.2, “mysql Commands”.

  • --no-auto-rehash, -A

    Deprecated form of -skip-auto-rehash. Use --disable-auto-rehash instead. See the description for --auto-rehash.

  • --no-beep, -b

    Do not beep when errors occur.

  • --no-named-commands, -g

    Deprecated, use --disable-named-commands instead.

  • --no-pager

    Deprecated form of --skip-pager. See the --pager option.

  • --no-tee

    Do not copy output to a file. Section 4.5.1.2, “mysql Commands”, discusses tee files further.

  • --one-database, -o

    Ignore statements except those for the default database named on the command line. This is useful for skipping updates to other databases in the binary log.

  • --pager[=command]

    Use the given command for paging query output. If the command is omitted, the default pager is the value of your PAGER environment variable. Valid pagers are less, more, cat [> filename], and so forth. This option works only on Unix. It does not work in batch mode. To disable paging, use --skip-pager. Section 4.5.1.2, “mysql Commands”, discusses output paging further.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --pipe, -W

    On Windows, connect to the server via a named pipe. This option applies only for connections to a local server, and only if the server supports named-pipe connections.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for the connection.

  • --prompt=format_str

    Set the prompt to the specified format. The default is mysql>. The special sequences that the prompt can contain are described in Section 4.5.1.2, “mysql Commands”.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the allowable values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --quick, -q

    Do not cache each query result, print each row as it is received. This may slow down the server if the output is suspended. With this option, mysql does not use the history file.

  • --raw, -r

    For tabular output, the “boxing” around columns enables one column value to be distinguished from another. For nontabular output (such as is produced in batch mode or when the --batch or --silent option is given), special characters are escaped in the output so they can be identified easily. Newline, tab, NUL, and backslash are written as \n, \t, \0, and \\. The --raw option disables this character escaping.

    The following example demonstrates tabular versus nontabular output and the use of raw mode to disable escaping:

    % mysql
    mysql> SELECT CHAR(92);
    +----------+
    | CHAR(92) |
    +----------+
    | \        |
    +----------+
    
    % mysql -s
    mysql> SELECT CHAR(92);
    CHAR(92)
    \\
    
    % mysql -s -r
    mysql> SELECT CHAR(92);
    CHAR(92)
    \
    
  • --reconnect

    If the connection to the server is lost, automatically try to reconnect. A single reconnect attempt is made each time the connection is lost. To suppress reconnection behavior, use --skip-reconnect.

  • --safe-updates, --i-am-a-dummy, -U

    Allow only those UPDATE and DELETE statements that specify which rows to modify by using key values. If you have set this option in an option file, you can override it by using --safe-updates on the command line. See Section 4.5.1.5, “mysql Tips”, for more information about this option.

  • --secure-auth

    Do not send passwords to the server in old (pre-4.1.1) format. This prevents connections except for servers that use the newer password format.

    MySQL Enterprise For expert advice on database security, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • --show-warnings

    Cause warnings to be shown after each statement if there are any. This option applies to interactive and batch mode.

  • --sigint-ignore

    Ignore SIGINT signals (typically the result of typing Control-C).

  • --silent, -s

    Silent mode. Produce less output. This option can be given multiple times to produce less and less output.

    This option results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the --raw option.

  • --skip-column-names, -N

    Do not write column names in results. The short format, -N is deprecated, use the long format instead.

  • --skip-line-numbers, -L

    Do not write line numbers for errors. Useful when you want to compare result files that include error messages. The short format, -L is deprecated, use the long format instead.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --ssl*

    Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section 5.5.7.3, “SSL Command Options”.

  • --table, -t

    Display output in table format. This is the default for interactive use, but can be used to produce table output in batch mode.

  • --tee=file_name

    Append a copy of output to the given file. This option does not work in batch mode. Section 4.5.1.2, “mysql Commands”, discusses tee files further.

  • --unbuffered, -n

    Flush the buffer after each query.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

  • --verbose, -v

    Verbose mode. Produce more output about what the program does. This option can be given multiple times to produce more and more output. (For example, -v -v -v produces table output format even in batch mode.)

  • --version, -V

    Display version information and exit.

  • --vertical, -E

    Print query output rows vertically (one line per column value). Without this option, you can specify vertical output for individual statements by terminating them with \G.

  • --wait, -w

    If the connection cannot be established, wait and retry instead of aborting.

  • --xml, -X

    Produce XML output.

    <field name="column_name">NULL</field>
    

    The output when --xml is used with mysql matches that of mysqldump --xml. See Section 4.5.4, “mysqldump — A Database Backup Program” for details.

    The XML output also uses an XML namespace, as shown here:

    shell> mysql --xml -uroot -e "SHOW VARIABLES LIKE 'version%'"
    <?xml version="1.0"?>
    
    <resultset statement="SHOW VARIABLES LIKE 'version%'" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <row>
    <field name="Variable_name">version</field>
    <field name="Value">5.0.40-debug</field>
    </row>
    
    <row>
    <field name="Variable_name">version_comment</field>
    <field name="Value">Source distribution</field>
    </row>
    
    <row>
    <field name="Variable_name">version_compile_machine</field>
    <field name="Value">i686</field>
    </row>
    
    <row>
    <field name="Variable_name">version_compile_os</field>
    <field name="Value">suse-linux-gnu</field>
    </row>
    </resultset>
    

    (See Bug#25946.)

You can also set the following variables by using --var_name=value. The --set-variable format is deprecated.

  • connect_timeout

    The number of seconds before connection timeout. (Default value is 0.)

  • max_allowed_packet

    The maximum packet length to send to or receive from the server. (Default value is 16MB.)

  • max_join_size

    The automatic limit for rows in a join when using --safe-updates. (Default value is 1,000,000.)

  • net_buffer_length

    The buffer size for TCP/IP and socket communication. (Default value is 16KB.)

  • select_limit

    The automatic limit for SELECT statements when using --safe-updates. (Default value is 1,000.)

On Unix, the mysql client writes a record of executed statements to a history file. By default, this file is named .mysql_history and is created in your home directory. To specify a different file, set the value of the MYSQL_HISTFILE environment variable.

The .mysql_history should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

If you do not want to maintain a history file, first remove .mysql_history if it exists, and then use either of the following techniques:

  • Set the MYSQL_HISTFILE variable to /dev/null. To cause this setting to take effect each time you log in, put the setting in one of your shell's startup files.

  • Create .mysql_history as a symbolic link to /dev/null:

    shell> ln -s /dev/null $HOME/.mysql_history
    

    You need do this only once.

4.5.1.2. mysql Commands

mysql sends each SQL statement that you issue to the server to be executed. There is also a set of commands that mysql itself interprets. For a list of these commands, type help or \h at the mysql> prompt:

mysql> help

List of all MySQL commands:
Note that all text commands must be first on line and end with ';'
?         (\?) Synonym for `help'.
clear     (\c) Clear command.
connect   (\r) Reconnect to the server. Optional arguments are db and host.
delimiter (\d) Set statement delimiter.
edit      (\e) Edit command with $EDITOR.
ego       (\G) Send command to mysql server, display result vertically.
exit      (\q) Exit mysql. Same as quit.
go        (\g) Send command to mysql server.
help      (\h) Display this help.
nopager   (\n) Disable pager, print to stdout.
notee     (\t) Don't write into outfile.
pager     (\P) Set PAGER [to_pager]. Print the query results via PAGER.
print     (\p) Print current command.
prompt    (\R) Change your mysql prompt.
quit      (\q) Quit mysql.
rehash    (\#) Rebuild completion hash.
source    (\.) Execute an SQL script file. Takes a file name as an argument.
status    (\s) Get status information from the server.
system    (\!) Execute a system shell command.
tee       (\T) Set outfile [to_outfile]. Append everything into given
               outfile.
use       (\u) Use another database. Takes database name as argument.
charset   (\C) Switch to another charset. Might be needed for processing
               binlog with multi-byte charsets.
warnings  (\W) Show warnings after every statement.
nowarning (\w) Don't show warnings after every statement.

For server side help, type 'help contents'

Each command has both a long and short form. The long form is not case sensitive; the short form is. The long form can be followed by an optional semicolon terminator, but the short form should not.

The use of short-form commands within multi-line /* ... */ comments is not supported.

  • help [arg], \h [arg], \? [arg], ? [arg]

    Display a help message listing the available mysql commands.

    If you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual. For more information, see Section 4.5.1.3, “mysql Server-Side Help”.

  • charset charset_name, \C charset_name

    Change the default character set and issue a SET NAMES statement. This enables the character set to remain synchronized on the client and server if mysql is run with auto-reconnect enabled (which is not recommended), because the specified character set is used for reconnects.

  • clear, \c

    Clear the current input. Use this if you change your mind about executing the statement that you are entering.

  • connect [db_name host_name]], \r [db_name host_name]]

    Reconnect to the server. The optional database name and host name arguments may be given to specify the default database or the host where the server is running. If omitted, the current values are used.

  • delimiter str, \d str

    Change the string that mysql interprets as the separator between SQL statements. The default is the semicolon character (“;”).

    The delimiter can be specified as an unquoted or quoted argument. Quoting can be done with either single quote (') or douple quote (") characters. To include a quote within a quoted string, either quote the string with the other quote character or escape the quote with a backslash (“\”) character. Backslash should be avoided outside of quoted strings because it is the escape character for MySQL. For an unquoted argument, the delmiter is read up to the first space or end of line. For a quoted argument, the delimiter is read up to the matching quote on the line.

    When the delimiter recognized by mysql is set to something other than the default of “;”, instances of that character are sent to the server without interpretation. However, the server itself still interprets “;” as a statement delimiter and processes statements accordingly. This behavior on the server side comes into play for multiple-statement execution (see Section 20.10.12, “C API Support for Multiple Statement Execution”), and for parsing the body of stored procedures and functions, triggers, and events (see Section 18.1, “Defining Stored Programs”).

  • edit, \e

    Edit the current input statement. mysql checks the values of the EDITOR and VISUAL environment variables to determine which editor to use. The default editor is vi if neither variable is set.

    The edit command works only in Unix.

  • ego, \G

    Send the current statement to the server to be executed and display the result using vertical format.

  • exit, \q

    Exit mysql.

  • go, \g

    Send the current statement to the server to be executed.

  • nopager, \n

    Disable output paging. See the description for pager.

    The nopager command works only in Unix.

  • notee, \t

    Disable output copying to the tee file. See the description for tee.

  • nowarning, \w

    Enable display of warnings after each statement.

  • pager [command], \P [command]

    Enable output paging. By using the --pager option when you invoke mysql, it is possible to browse or search query results in interactive mode with Unix programs such as less, more, or any other similar program. If you specify no value for the option, mysql checks the value of the PAGER environment variable and sets the pager to that.

    Output paging can be enabled interactively with the pager command and disabled with nopager. The command takes an optional argument; if given, the paging program is set to that. With no argument, the pager is set to the pager that was set on the command line, or stdout if no pager was specified.

    Output paging works only in Unix because it uses the popen() function, which does not exist on Windows. For Windows, the tee option can be used instead to save query output, although it is not as convenient as pager for browsing output in some situations.

  • print, \p

    Print the current input statement without executing it.

  • prompt [str], \R [str]

    Reconfigure the mysql prompt to the given string. The special character sequences that can be used in the prompt are described later in this section.

    If you specify the prompt command with no argument, mysql resets the prompt to the default of mysql>.

  • quit, \q

    Exit mysql.

  • rehash, \#

    Rebuild the completion hash that enables database, table, and column name completion while you are entering statements. (See the description for the --auto-rehash option.)

  • source file_name, \. file_name

    Read the named file and executes the statements contained therein. On Windows, you can specify path name separators as / or \\.

  • status, \s

    Provide status information about the connection and the server you are using. If you are running in --safe-updates mode, status also prints the values for the mysql variables that affect your queries.

  • system command, \! command

    Execute the given command using your default command interpreter.

    The system command works only in Unix.

  • tee [file_name], \T [file_name]

    By using the --tee option when you invoke mysql, you can log statements and their output. All the data displayed on the screen is appended into a given file. This can be very useful for debugging purposes also. mysql flushes results to the file after each statement, just before it prints its next prompt.

    You can enable this feature interactively with the tee command. Without a parameter, the previous file is used. The tee file can be disabled with the notee command. Executing tee again re-enables logging.

  • use db_name, \u db_name

    Use db_name as the default database.

  • warnings, \W

    Enable display of warnings after each statement (if there are any).

Here are a few tips about the pager command:

  • You can use it to write to a file and the results go only to the file:

    mysql> pager cat > /tmp/log.txt
    

    You can also pass any options for the program that you want to use as your pager:

    mysql> pager less -n -i -S
    
  • In the preceding example, note the -S option. You may find it very useful for browsing wide query results. Sometimes a very wide result set is difficult to read on the screen. The -S option to less can make the result set much more readable because you can scroll it horizontally using the left-arrow and right-arrow keys. You can also use -S interactively within less to switch the horizontal-browse mode on and off. For more information, read the less manual page:

    shell> man less
    
  • The -F and -X options may be used with less to cause it to exit if output fits on one screen, which is convenient when no scrolling is necessary:

    mysql> pager less -n -i -S -F -X
    
  • You can specify very complex pager commands for handling query output:

    mysql> pager cat | tee /dr1/tmp/res.txt \
              | tee /dr2/tmp/res2.txt | less -n -i -S
    

    In this example, the command would send query results to two files in two different directories on two different file systems mounted on /dr1 and /dr2, yet still display the results onscreen via less.

You can also combine the tee and pager functions. Have a tee file enabled and pager set to less, and you are able to browse the results using the less program and still have everything appended into a file the same time. The difference between the Unix tee used with the pager command and the mysql built-in tee command is that the built-in tee works even if you do not have the Unix tee available. The built-in tee also logs everything that is printed on the screen, whereas the Unix tee used with pager does not log quite that much. Additionally, tee file logging can be turned on and off interactively from within mysql. This is useful when you want to log some queries to a file, but not others.

The prompt command reconfigures the default mysql> prompt. The string for defining the prompt can contain the following special sequences.

OptionDescription
\cA counter that increments for each statement you issue
\DThe full current date
\dThe default database
\hThe server host
\lThe current delimiter
\mMinutes of the current time
\nA newline character
\OThe current month in three-letter format (Jan, Feb, …)
\oThe current month in numeric format
\Pam/pm
\pThe current TCP/IP port or socket file
\RThe current time, in 24-hour military time (0–23)
\rThe current time, standard 12-hour time (1–12)
\SSemicolon
\sSeconds of the current time
\tA tab character
\U

Your full user_name@host_name account name

\uYour user name
\vThe server version
\wThe current day of the week in three-letter format (Mon, Tue, …)
\YThe current year, four digits
\yThe current year, two digits
\_A space
A space (a space follows the backslash)
\'Single quote
\"Double quote
\\A literal “\” backslash character
\x

x, for any “x” not listed above

You can set the prompt in several ways:

  • Use an environment variable. You can set the MYSQL_PS1 environment variable to a prompt string. For example:

    shell> export MYSQL_PS1="(\u@\h) [\d]> "
    
  • Use a command-line option. You can set the --prompt option on the command line to mysql. For example:

    shell> mysql --prompt="(\u@\h) [\d]> "
    (user@host) [database]>
    
  • Use an option file. You can set the prompt option in the [mysql] group of any MySQL option file, such as /etc/my.cnf or the .my.cnf file in your home directory. For example:

    [mysql]
    prompt=(\\u@\\h) [\\d]>\\_
    

    In this example, note that the backslashes are doubled. If you set the prompt using the prompt option in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of allowable prompt options and the set of special escape sequences that are recognized in option files. (These sequences are listed in Section 4.2.3.3, “Using Option Files”.) The overlap may cause you problems if you use single backslashes. For example, \s is interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time in HH:MM:SS> format:

    [mysql]
    prompt="\\r:\\m:\\s> "
    
  • Set the prompt interactively. You can change your prompt interactively by using the prompt (or \R) command. For example:

    mysql> prompt (\u@\h) [\d]>\_
    PROMPT set to '(\u@\h) [\d]>\_'
    (user@host) [database]>
    (user@host) [database]> prompt
    Returning to default PROMPT of mysql>
    mysql>
    

4.5.1.3. mysql Server-Side Help

mysql> help search_string

If you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in the mysql database be initialized with help topic information (see Section 5.1.9, “Server-Side Help”).

If there is no match for the search string, the search fails:

mysql> help me

Nothing found
Please try to run 'help contents' for a list of all accessible topics

Use help contents to see a list of the help categories:

mysql> help contents
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the
following categories:
   Account Management
   Administration
   Data Definition
   Data Manipulation
   Data Types
   Functions
   Functions and Modifiers for Use with GROUP BY
   Geographic Features
   Language Structure
   Plugins
   Storage Engines
   Stored Routines
   Table Maintenance
   Transactions
   Triggers

If the search string matches multiple items, mysql shows a list of matching topics:

mysql> help logs
Many help items for your request exist.
To make a more specific request, please type 'help <item>',
where <item> is one of the following topics:
   SHOW
   SHOW BINARY LOGS
   SHOW ENGINE
   SHOW LOGS

Use a topic as the search string to see the help entry for that topic:

mysql> help show binary logs
Name: 'SHOW BINARY LOGS'
Description:
Syntax:
SHOW BINARY LOGS
SHOW MASTER LOGS

Lists the binary log files on the server. This statement is used as
part of the procedure described in [purge-binary-logs], that shows how
to determine which logs can be purged.

mysql> SHOW BINARY LOGS;
+---------------+-----------+
| Log_name      | File_size |
+---------------+-----------+
| binlog.000015 |    724935 |
| binlog.000016 |    733481 |
+---------------+-----------+

4.5.1.4. Executing SQL Statements from a Text File

The mysql client typically is used interactively, like this:

shell> mysql db_name

However, it is also possible to put your SQL statements in a file and then tell mysql to read its input from that file. To do so, create a text file text_file that contains the statements you wish to execute. Then invoke mysql as shown here:

shell> mysql db_name < text_file

If you place a USE db_name statement as the first statement in the file, it is unnecessary to specify the database name on the command line:

shell> mysql < text_file

If you are already running mysql, you can execute an SQL script file using the source command or \. command:

mysql> source file_name
mysql> \. file_name

Sometimes you may want your script to display progress information to the user. For this you can insert statements like this:

SELECT '<info_to_display>' AS ' ';

The statement shown outputs <info_to_display>.

As of MySQL 6.0.4, mysql ignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not cause mysql to change its default character set. To do that, invoke mysql with an option such as --default-character-set=utf8.

For more information about batch mode, see Section 3.5, “Using mysql in Batch Mode”.

4.5.1.5. mysql Tips

This section describes some techniques that can help you use mysql more effectively.

4.5.1.5.1. Displaying Query Results Vertically

Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output:

mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G
*************************** 1. row ***************************
  msg_nro: 3068
     date: 2000-03-01 23:29:50
time_zone: +0200
mail_from: Monty
    reply: monty@no.spam.com
  mail_to: "Thimble Smith" <tim@no.spam.com>
      sbj: UTF-8
      txt: >>>>> "Thimble" == Thimble Smith writes:

Thimble> Hi.  I think this is a good idea.  Is anyone familiar
Thimble> with UTF-8 or Unicode? Otherwise, I'll put this on my
Thimble> TODO list and see what happens.

Yes, please do that.

Regards,
Monty
     file: inbox-jani-1
     hash: 190402944
1 row in set (0.09 sec)
4.5.1.5.2. Using the --safe-updates Option

For beginners, a useful startup option is --safe-updates (or --i-am-a-dummy, which has the same effect). It is helpful for cases when you might have issued a DELETE FROM tbl_name statement but forgotten the WHERE clause. Normally, such a statement deletes all rows from the table. With --safe-updates, you can delete rows only by specifying the key values that identify them. This helps prevent accidents.

When you use the --safe-updates option, mysql issues the following statement when it connects to the MySQL server:

SET sql_safe_updates=1, sql_select_limit=1000, sql_max_join_size=1000000;

See Section 5.1.5, “Session System Variables”.

The SET statement has the following effects:

  • You are not allowed to execute an UPDATE or DELETE statement unless you specify a key constraint in the WHERE clause or provide a LIMIT clause (or both). For example:

    UPDATE tbl_name SET not_key_column=val WHERE key_column=val;
    
    UPDATE tbl_name SET not_key_column=val LIMIT 1;
    
  • The server limits all large SELECT results to 1,000 rows unless the statement includes a LIMIT clause.

  • The server aborts multiple-table SELECT statements that probably need to examine more than 1,000,000 row combinations.

To specify limits different from 1,000 and 1,000,000, you can override the defaults by using the --select_limit and --max_join_size options:

shell> mysql --safe-updates --select_limit=500 --max_join_size=10000
4.5.1.5.3. Disabling mysql Auto-Reconnect

If the mysql client loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even if mysql succeeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it:

mysql> SET @a=1;
Query OK, 0 rows affected (0.05 sec)

mysql> INSERT INTO t VALUES(@a);
ERROR 2006: MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    1
Current database: test

Query OK, 1 row affected (1.30 sec)

mysql> SELECT * FROM t;
+------+
| a    |
+------+
| NULL |
+------+
1 row in set (0.05 sec)

The @a user variable has been lost with the connection, and after the reconnection it is undefined. If it is important to have mysql terminate with an error if the connection has been lost, you can start the mysql client with the --skip-reconnect option.

For more information about auto-reconnect and its effect on state information when a reconnection occurs, see Section 20.10.11, “Controlling Automatic Reconnection Behavior”.

4.5.2. mysqladmin — Client for Administering a MySQL Server

mysqladmin is a client for performing administrative operations. You can use it to check the server's configuration and current status, to create and drop databases, and more.

Invoke mysqladmin like this:

shell> mysqladmin [options] command [command-arg] [command [command-arg]] ...

mysqladmin supports the commands described in the following list. Some of the commands take an argument following the command name.

  • create db_name

    Create a new database named db_name.

  • debug

    Tell the server to write debug information to the error log.

    This includes information about the Event Scheduler. See Section 18.4.5, “Event Scheduler Status”.

  • drop db_name

    Delete the database named db_name and all its tables.

  • extended-status

    Display the server status variables and their values.

    MySQL Enterprise For expert advice on using server status variables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • flush-hosts

    Flush all information in the host cache.

  • flush-logs

    Flush all logs.

  • flush-privileges

    Reload the grant tables (same as reload).

  • flush-status

    Clear status variables.

  • flush-tables

    Flush all tables.

  • flush-threads

    Flush the thread cache.

  • kill id,id,...

    Kill server threads. If multiple thread ID values are given, there must be no spaces in the list.

  • old-password new-password

    This is like the password command but stores the password using the old (pre-4.1) password-hashing format. (See Section 5.5.6.3, “Password Hashing in MySQL”.)

    MySQL Enterprise For expert advice on the security implications of using the old-password command, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • password new-password

    Set a new password. This changes the password to new-password for the account that you use with mysqladmin for connecting to the server. Thus, the next time you invoke mysqladmin (or any other client program) using the same account, you will need to specify the new password.

    If the new-password value contains spaces or other characters that are special to your command interpreter, you need to enclose it within quotes. On Windows, be sure to use double quotes rather than single quotes; single quotes are not stripped from the password, but rather are interpreted as part of the password. For example:

    shell> mysqladmin password "my new password"
    

    Caution

    Do not use this command used if the server was started with the --skip-grant-tables option. No password change will be applied. This is true even if you precede the password command with flush-privileges on the same command line to re-enable the grant tables because the flush operation occurs after you connect. However, you can use mysqladmin flush-privileges to re-enable the grant table and then use a separate mysqladmin password command to change the password.

  • ping

    Check whether the server is alive. The return status from mysqladmin is 0 if the server is running, 1 if it is not. This is 0 even in case of an error such as Access denied, because this means that the server is running but refused the connection, which is different from the server not running.

  • processlist

    Show a list of active server threads. This is like the output of the SHOW PROCESSLIST statement. If the --verbose option is given, the output is like that of SHOW FULL PROCESSLIST. (See Section 12.5.6.30, “SHOW PROCESSLIST Syntax”.)

  • reload

    Reload the grant tables.

  • refresh

    Flush all tables and close and open log files.

  • shutdown

    Stop the server.

  • start-slave

    Start replication on a slave server.

  • status

    Display a short server status message.

  • stop-slave

    Stop replication on a slave server.

  • variables

    Display the server system variables and their values.

    MySQL Enterprise For expert advice on using server system variables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • version

    Display version information from the server.

All commands can be shortened to any unique prefix. For example:

shell> mysqladmin proc stat
+----+-------+-----------+----+---------+------+-------+------------------+
| Id | User  | Host      | db | Command | Time | State | Info             |
+----+-------+-----------+----+---------+------+-------+------------------+
| 51 | monty | localhost |    | Query   | 0    |       | show processlist |
+----+-------+-----------+----+---------+------+-------+------------------+
Uptime: 1473624  Threads: 1  Questions: 39487
Slow queries: 0  Opens: 541  Flush tables: 1
Open tables: 19  Queries per second avg: 0.0268

The mysqladmin status command result displays the following values:

  • Uptime

    The number of seconds the MySQL server has been running.

  • Threads

    The number of active threads (clients).

  • Questions

    The number of questions (queries) from clients since the server was started.

  • Slow queries

    The number of queries that have taken more than long_query_time seconds. See Section 5.2.5, “The Slow Query Log”.

  • Opens

    The number of tables the server has opened.

  • Flush tables

    The number of flush-*, refresh, and reload commands the server has executed.

  • Open tables

    The number of tables that currently are open.

  • Memory in use

    The amount of memory allocated directly by mysqld. This value is displayed only when MySQL has been compiled with --with-debug=full.

  • Maximum memory used

    The maximum amount of memory allocated directly by mysqld. This value is displayed only when MySQL has been compiled with --with-debug=full.

If you execute mysqladmin shutdown when connecting to a local server using a Unix socket file, mysqladmin waits until the server's process ID file has been removed, to ensure that the server has stopped properly.

Table 4.3. mysqladmin Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--compresscompressCompress all information sent between the client and the server   
--connect_timeout=secondsconnect_timeoutThe number of seconds before connection timeout   
--count=#countThe number of iterations to make for repeated command execution   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--forceforceContinue even if an SQL error occurs   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--no-beepno-beepDo not beep when errors occur   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server via a named pipe   
--port=port_numportThe TCP/IP port number to use for the connection   
--protocol=typeprotocolThe connection protocol to use   
--relativerelativeShow the difference between the current and previous values when used with the --sleep option   
--shutdown_timeout=secondsshutdown_timeoutThe maximum number of seconds to wait for server shutdown   
--silentsilentSilent mode   
--sleep=delaysleepExecute commands repeatedly, sleeping for delay seconds in between   
--socket=pathsocketFor connections to localhost   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--user=user_name,userThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   
--verticalverticalPrint query output rows vertically (one line per column value)   
--waitwaitIf the connection cannot be established, wait and retry instead of aborting   

mysqladmin supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help, -?

    Display a help message and exit.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --compress, -C

    Compress all information sent between the client and the server if both support compression.

  • --count=N, -c N

    The number of iterations to make for repeated command execution if the --sleep option is given.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysqladmin.trace'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --default-character-set=charset_name

    Use charset_name as the default character set. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --force, -f

    Do not ask for confirmation for the drop db_name command. With multiple commands, continue even if an error occurs.

  • --host=host_name, -h host_name

    Connect to the MySQL server on the given host.

  • --no-beep, -b

    Suppress the warning beep that is emitted by default for errors such as a failure to connect to the server.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --pipe, -W

    On Windows, connect to the server via a named pipe. This option applies only for connections to a local server, and only if the server supports named-pipe connections.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for the connection.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the allowable values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --relative, -r

    Show the difference between the current and previous values when used with the --sleep option. Currently, this option works only with the extended-status command.

  • --silent, -s

    Exit silently if a connection to the server cannot be established.

  • --sleep=delay, -i delay

    Execute commands repeatedly, sleeping for delay seconds in between. The --count option determines the number of iterations. If --count is not given, mysqladmin executes commands indefinitely until interrupted.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --ssl*

    Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section 5.5.7.3, “SSL Command Options”.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

  • --verbose, -v

    Verbose mode. Print more information about what the program does.

  • --version, -V

    Display version information and exit.

  • --vertical, -E

    Print output vertically. This is similar to --relative, but prints output vertically.

  • --wait[=count], -w[count]

    If the connection cannot be established, wait and retry instead of aborting. If a count value is given, it indicates the number of times to retry. The default is one time.

You can also set the following variables by using --var_name=value The --set-variable format is deprecated. syntax:

  • connect_timeout

    The maximum number of seconds before connection timeout. The default value is 43200 (12 hours).

  • shutdown_timeout

    The maximum number of seconds to wait for server shutdown. The default value is 3600 (1 hour).

4.5.3. mysqlcheck — A Table Maintenance Program

The mysqlcheck client performs table maintenance: It checks, repairs, optimizes, or analyzes tables.

Each table is locked and therefore unavailable to other sessions while it is being processed. Table maintenance operations can be time-consuming, particularly for large tables. If you use the --databases or --all-databases option to process all tables in one or more databases, an invocation of mysqlcheck might take a long time. (This is also true for mysql_upgrade because that program invokes mysqlcheck to check all tables and repair them if necessary.)

mysqlcheck is similar in function to myisamchk, but works differently. The main operational difference is that mysqlcheck must be used when the mysqld server is running, whereas myisamchk should be used when it is not. The benefit of using mysqlcheck is that you do not have to stop the server to perform table maintenance.

mysqlcheck uses the SQL statements CHECK TABLE, REPAIR TABLE, ANALYZE TABLE, and OPTIMIZE TABLE in a convenient way for the user. It determines which statements to use for the operation you want to perform, and then sends the statements to the server to be executed. For details about which storage engines each statement works with, see the descriptions for those statements in Section 12.5.2, “Table Maintenance Statements”.

The MyISAM storage engine supports all four maintenance operations, so mysqlcheck can be used to perform any of them on MyISAM tables. Other storage engines do not necessarily support all operations. In such cases, an error message is displayed. For example, if test.t is a MEMORY table, an attempt to check it produces this result:

shell> mysqlcheck test t
test.t
note     : The storage engine for the table doesn't support check

If mysqlcheck is unable to repair a table, see Section 2.11.4, “Rebuilding or Repairing Tables or Indexes” for manual table repair strategies. This will be the case, for example, for InnoDB tables, which can be checked with CHECK TABLE, but not repaired with REPAIR TABLE.

The use of mysqlcheck with partitioned tables is not supported before MySQL 6.0.6.

Caution

It is best to make a backup of a table before performing a table repair operation; under some circumstances the operation might cause data loss. Possible causes include but are not limited to file system errors.

There are three general ways to invoke mysqlcheck:

shell> mysqlcheck [options] db_name [tables]
shell> mysqlcheck [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqlcheck [options] --all-databases

If you do not name any tables following db_name or if you use the --databases or --all-databases option, entire databases are checked.

mysqlcheck has a special feature compared to other client programs. The default behavior of checking tables (--check) can be changed by renaming the binary. If you want to have a tool that repairs tables by default, you should just make a copy of mysqlcheck named mysqlrepair, or make a symbolic link to mysqlcheck named mysqlrepair. If you invoke mysqlrepair, it repairs tables.

The following names can be used to change mysqlcheck default behavior.

mysqlrepairThe default option is --repair
mysqlanalyzeThe default option is --analyze
mysqloptimizeThe default option is --optimize

Table 4.4. mysqlcheck Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--all-databasesall-databasesCheck all tables in all databases   
--all-in-1all-in-1Execute a single statement for each database that names all the tables from that database   
--analyzeanalyzeAnalyze the tables   
--auto-repairauto-repairIf a checked table is corrupted, automatically fix it   
--character-sets-dir=pathcharacter-sets-dirThe directory where character sets are installed   
--checkcheckCheck the tables for errors   
--check-only-changedcheck-only-changedCheck only tables that have changed since the last check   
--check-upgradecheck-upgradeInvoke CHECK TABLE with the FOR UPGRADE option   
--compresscompressCompress all information sent between the client and the server   
--databasesdatabasesProcess all tables in the named databases   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--extendedextendedCheck and repair tables   
--fastfastCheck only tables that have not been closed properly   
--fix-db-namesfix-db-namesConvert database names to 5.1 format   
--fix-table-namesfix-table-namesConvert table names to 5.1 format   
--forceforceContinue even if an SQL error occurs   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--medium-checkmedium-checkDo a check that is faster than an --extended operation   
--optimizeoptimizeOptimize the tables   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server via a named pipe   
--port=port_numportThe TCP/IP port number to use for the connection   
--protocol=typeprotocolThe connection protocol to use   
--quickquickThe fastest method of checking   
--repairrepairPerform a repair that can fix almost anything except unique keys that are not unique   
--silentsilentSilent mode   
--socket=pathsocketFor connections to localhost   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--tablestablesOverrides the --databases or -B option   
--use-frmuse-frmFor repair operations on MyISAM tables   
--user=user_name,userThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   

mysqlcheck supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help, -?

    Display a help message and exit.

  • --all-databases, -A

    Check all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.

  • --all-in-1, -1

    Instead of issuing a statement for each table, execute a single statement for each database that names all the tables from that database to be processed.

  • --analyze, -a

    Analyze the tables.

    MySQL Enterprise For expert advice on optimizing tables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • --auto-repair

    If a checked table is corrupted, automatically fix it. Any necessary repairs are done after all tables have been checked.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --check, -c

    Check the tables for errors. This is the default operation.

  • --check-only-changed, -C

    Check only tables that have changed since the last check or that have not been closed properly.

  • --check-upgrade, -g

    Invoke CHECK TABLE with the FOR UPGRADE option to check tables for incompatibilities with the current version of the server. This option automatically enables the --fix-db-names and --fix-table-names options.

  • --compress

    Compress all information sent between the client and the server if both support compression.

  • --databases, -B

    Process all tables in the named databases. Normally, mysqlcheck treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --default-character-set=charset_name

    Use charset_name as the default character set. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --extended, -e

    If you are using this option to check tables, it ensures that they are 100% consistent but takes a long time.

    If you are using this option to repair tables, it runs an extended repair that may not only take a long time to execute, but may produce a lot of garbage rows also!

  • --fast, -F

    Check only tables that have not been closed properly.

  • --fix-db-names

    Convert database names to 5.1 format. Only database names that contain special characters are affected.

  • --fix-table-names

    Convert table names to 5.1 format. Only table names that contain special characters are affected. As of MySQL 6.0.5, this option also applies to views.

  • --force, -f

    Continue even if an SQL error occurs.

  • --host=host_name, -h host_name

    Connect to the MySQL server on the given host.

  • --medium-check, -m

    Do a check that is faster than an --extended operation. This finds only 99.99% of all errors, which should be good enough in most cases.

  • --optimize, -o

    Optimize the tables.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --pipe, -W

    On Windows, connect to the server via a named pipe. This option applies only for connections to a local server, and only if the server supports named-pipe connections.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for the connection.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the allowable values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --quick, -q

    If you are using this option to check tables, it prevents the check from scanning the rows to check for incorrect links. This is the fastest check method.

    If you are using this option to repair tables, it tries to repair only the index tree. This is the fastest repair method.

  • --repair, -r

    Perform a repair that can fix almost anything except unique keys that are not unique.

  • --silent, -s

    Silent mode. Print only error messages.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --ssl*

    Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section 5.5.7.3, “SSL Command Options”.

  • --tables

    Override the --databases or -B option. All name arguments following the option are regarded as table names.

  • --use-frm

    For repair operations on MyISAM tables, get the table structure from the .frm file so that the table can be repaired even if the .MYI header is corrupted.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

  • --verbose, -v

    Verbose mode. Print information about the various stages of program operation.

  • --version, -V

    Display version information and exit.

4.5.4. mysqldump — A Database Backup Program

The mysqldump client is a backup program originally written by Igor Romanenko. It can be used to dump a database or a collection of databases for backup or transfer to another SQL server (not necessarily a MySQL server). The dump typically contains SQL statements to create the table, populate it, or both. However, mysqldump can also be used to generate files in CSV, other delimited text, or XML format.

If you are doing a backup on the server and your tables all are MyISAM tables, consider using the mysqlhotcopy instead because it can accomplish faster backups and faster restores. See Section 4.6.10, “mysqlhotcopy — A Database Backup Program”.

There are three general ways to invoke mysqldump:

shell> mysqldump [options] db_name [tables]
shell> mysqldump [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqldump [options] --all-databases

If you do not name any tables following db_name or if you use the --databases or --all-databases option, entire databases are dumped.

mysqldump does not dump the INFORMATION_SCHEMA database. If you name that database explicitly on the command line, mysqldump silently ignores it.

To get a list of the options your version of mysqldump supports, execute mysqldump --help.

Some mysqldump options are shorthand for groups of other options. --opt and --compact fall into this category. For example, use of --opt is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. Note that all of the options that --opt stands for also are on by default because --opt is on by default.

To reverse the effect of a group option, uses its --skip-xxx form (--skip-opt or --skip-compact). It is also possible to select only part of the effect of a group option by following it with options that enable or disable specific features. Here are some examples:

When you selectively enable or disable the effect of a group option, order is important because options are processed first to last. For example, --disable-keys --lock-tables --skip-opt would not have the intended effect; it is the same as --skip-opt by itself.

mysqldump can retrieve and dump table contents row by row, or it can retrieve the entire content from a table and buffer it in memory before dumping it. Buffering in memory can be a problem if you are dumping large tables. To dump tables row by row, use the --quick option (or --opt, which enables --quick). The --opt option (and hence --quick) is enabled by default in MySQL 6.0; to enable memory buffering, use --skip-quick.

If you are using a recent version of mysqldump to generate a dump to be reloaded into a very old MySQL server, you should not use the --opt or --extended-insert option. Use --skip-opt instead.

Table 4.5. mysqldump Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--add-drop-databaseadd-drop-databaseAdd a DROP DATABASE statement before each CREATE DATABASE statement   
--add-drop-tableadd-drop-tableAdd a DROP TABLE statement before each CREATE TABLE statement   
--add-locksadd-locksSurround each table dump with LOCK TABLES and UNLOCK TABLES statements   
--all-databasesall-databasesDump all tables in all databases   
--allow-keywordsallow-keywordsAllow creation of column names that are keywords   
--apply-slave-statementsapply-slave-statementsInclude STOP SLAVE prior to CHANGE MASTER statement and START SLAVE at end of output6.0.4  
--commentscommentsAdd comments to the dump file   
--compactcompactProduce less verbose output   
--compatible=name[,name,...]compatibleProduce output that is more compatible with other database systems or with older MySQL servers   
--complete-insertcomplete-insertUse complete INSERT statements that include column names   
--create-optionscreate-optionsInclude all MySQL-specific table options in the CREATE TABLE statements   
--databasesdatabasesDump several databases   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--delayed-insertdelayed-insertWrite INSERT DELAYED statements rather than INSERT statements   
--delete-master-logsdelete-master-logsOn a master replication server, delete the binary logs after performing the dump operation   
--disable-keysdisable-keysFor each table, surround the INSERT statements with disable and enable keys statements   
--dump-datedump-dateInclude dump date in "Dump completed on" comment if --comments is given6.0.4  
--dump-slave[=value]dump-slaveInclude CHANGE MASTER statement that lists binary log coordinates of slave's master6.0.4  
--eventseventsDump events from the dumped databases   
--extended-insertextended-insertUse multiple-row INSERT syntax that include several VALUES lists   
--fields-enclosed-by=stringfields-enclosed-byThis option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-escaped-byfields-escaped-byThis option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-terminated-by=stringfields-terminated-byThis option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--lock-all-tablesfirst-slaveDeprecated. Now renamed to --lock-all-tables   
--flush-logsflush-logsFlush the MySQL server log files before starting the dump   
--flush-privilegesflush-privilegesEmit a FLUSH PRIVILEGES statement after dumping the mysql database   
--help Display help message and exit   
--hex-blobhex-blobDump binary columns using hexadecimal notation (for example, 'abc' becomes 0x616263)   
--ignore-table=db_name.tbl_nameignore-tableDo not dump the given table   
--include-master-host-portinclude-master-host-portInclude MASTER_HOST/MASTER_PORT options in CHANGE MASTER statement produced with --dump-slave6.0.4  
--insert-ignoreinsert-ignoreWrite INSERT statements with the IGNORE option   
--lines-terminated-by=stringlines-terminated-byThis option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE   
--lock-all-tableslock-all-tablesLock all tables across all databases   
--lock-tableslock-tablesLock all tables before dumping them   
--log-error=file_namelog-errorAppend warnings and errors to the named file   
--master-data[=value]master-dataWrite the binary log file name and position to the output   
--max_allowed_packet=valuemax_allowed_packetThe maximum packet length to send to or receive from the server   
--net_buffer_length=valuenet_buffer_lengthThe buffer size for TCP/IP and socket communication   
--no-autocommitno-autocommitEnclose the INSERT statements for each dumped table within SET autocommit = 0 and COMMIT statements   
--no-create-dbno-create-dbThis option suppresses the CREATE DATABASE statements   
--no-create-infono-create-infoDo not write CREATE TABLE statements that re-create each dumped table   
--no-datano-dataDo not write any table row information (that is, do not dump table contents)   
--no-set-namesno-set-namesTurn off complete-insert   
--optoptThis option is shorthand; it is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset.   
--order-by-primaryorder-by-primarySorts each table's rows by its primary key, or by its first unique index   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server via a named pipe   
--port=port_numportThe TCP/IP port number to use for the connection   
--quickquickRetrieve rows for a table from the server a row at a time   
--quote-namesquote-namesQuote database, table, and column names within backtick characters   
--replacereplaceWrite REPLACE statements rather than INSERT statements   
--result-file=fileresult-fileDirect output to a given file   
--routinesroutinesDump stored routines (procedures and functions) from the dumped databases   
--set-charsetset-charsetAdd SET NAMES default_character_set to the output   
--single-transactionsingle-transactionThis option issues a BEGIN SQL statement before dumping data from the server   
--skip-add-drop-tableskip-add-drop-tableDo not add   
--skip-add-locksskip-add-locksDo not add locks   
--skip-commentsskip-commentsDo not add comments to the dump file   
--skip-compactskip-compactTurn off compact   
--skip-disable-keysskip-disable-keysDo not disable keys   
--skip-extended-insertskip-extended-insertTurn off extended-insert   
--skip-optskip-optTurn off the options set by opt   
--skip-quickskip-quickDo not retrieve rows for a table from the server a row at a time   
--skip-quote-namesskip-quote-namesTurn off quote names   
--skip-set-charsetskip-set-charsetSuppress the SET NAMES statement   
--skip-triggersskip-triggersTurn off triggers   
--skip-tz-utcskip-tz-utcTurn off tz-utc   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--tab=pathtabProduce tab-separated data files   
--tablestablesOverride the --databases or -B option   
--triggerstriggersDump triggers for each dumped table   
--tz-utctz-utcAdd SET TIME_ZONE='+00:00' to the dump file   
--verbose Verbose mode   
--version Display version information and exit   
--where='where_condition'whereDump only rows selected by the given WHERE condition   
--xmlxmlProduce XML output   

mysqldump supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help, -?

    Display a help message and exit.

  • --add-drop-database

    Add a DROP DATABASE statement before each CREATE DATABASE statement.

  • --add-drop-table

    Add a DROP TABLE statement before each CREATE TABLE statement.

  • --add-locks

    Surround each table dump with LOCK TABLES and UNLOCK TABLES statements. This results in faster inserts when the dump file is reloaded. See Section 7.2.25, “Speed of INSERT Statements”.

  • --all-databases, -A

    Dump all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.

  • --allow-keywords

    Allow creation of column names that are keywords. This works by prefixing each column name with the table name.

  • --apply-slave-statements

    For a slave dump produced with the --dump-slave option, add a STOP SLAVE statement before the CHANGE MASTER TO statement and a START SLAVE statement at the end of the output. This option was added in MySQL 6.0.4.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --comments, -i

    Write additional information in the dump file such as program version, server version, and host. This option is enabled by default. To suppress this additional information, use --skip-comments.

  • --compact

    Produce less verbose output. This option enables the --skip-add-drop-table, --skip-add-locks, --skip-comments, --skip-disable-keys, and --skip-set-charset options.

  • --compatible=name

    Produce output that is more compatible with other database systems or with older MySQL servers. The value of name can be ansi, mysql323, mysql40, postgresql, oracle, mssql, db2, maxdb, no_key_options, no_table_options, or no_field_options. To use several values, separate them by commas. These values have the same meaning as the corresponding options for setting the server SQL mode. See Section 5.1.8, “Server SQL Modes”.

    This option does not guarantee compatibility with other servers. It only enables those SQL mode values that are currently available for making dump output more compatible. For example, --compatible=oracle does not map data types to Oracle types or use Oracle comment syntax.

    This option requires a server version of 4.1.0 or higher. With older servers, it does nothing.

  • --complete-insert, -c

    Use complete INSERT statements that include column names.

  • --compress, -C

    Compress all information sent between the client and the server if both support compression.

  • --create-options

    Include all MySQL-specific table options in the CREATE TABLE statements.

  • --databases, -B

    Dump several databases. Normally, mysqldump treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names. CREATE DATABASE and USE statements are included in the output before each new database.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default value is 'd:t:o,/tmp/mysqldump.trace'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --default-character-set=charset_name

    Use charset_name as the default character set. See Section 9.2, “The Character Set Used for Data and Sorting”. If no character set is specified, mysqldump uses utf8, and earlier versions use latin1.

    This option has no effect for output data files produced by using the --tab option. See the description for that option.

  • --delayed-insert

    Write INSERT DELAYED statements rather than INSERT statements.

  • --delete-master-logs

    On a master replication server, delete the binary logs after performing the dump operation. This option automatically enables --master-data.

  • --disable-keys, -K

    For each table, surround the INSERT statements with /*!40000 ALTER TABLE tbl_name DISABLE KEYS */; and /*!40000 ALTER TABLE tbl_name ENABLE KEYS */; statements. This makes loading the dump file faster because the indexes are created after all rows are inserted. This option is effective only for nonunique indexes of MyISAM tables.

  • --dump-date

    mysqldump produces a -- Dump completed on DATE comment at the end of the dump if the --comments option is given. However, the date causes dump files for identical data take at different times to appear to be different. --dump-date and --skip-dump-date control whether the date is added to the comment. The default is --dump-date (include the date in the comment). --skip-dump-date suppresses date printing. This option was added in MySQL 6.0.4.

  • --dump-slave[=value]

    This option is similar to --master-data except that it is used to dump a replication slave server to produce a dump file that can be used to set up another server as a slave that has the same master as the dumped server. It causes the dump output to include a CHANGE MASTER TO statement that indicates the binary log coordinates (file name and position) of the dumped slave's master (rather than the coordinates of the dumped server, as is done by the --master-data option). These are the master server coordinates from which the slave should start replicating. This option was added in MySQL 6.0.4.

    The option value is handled the same way as for --master-data and has the same effect as --master-data in terms of enabling or disabling other options and in how locking is handled.

    In conjunction with --dump-slave, the --apply-slave-statements and --include-master-host-port options can also be used.

  • --events, -E

    Dump events from the dumped databases.

  • --extended-insert, -e

    Use multiple-row INSERT syntax that include several VALUES lists. This results in a smaller dump file and speeds up inserts when the file is reloaded.

  • --fields-terminated-by=..., --fields-enclosed-by=..., --fields-optionally-enclosed-by=..., --fields-escaped-by=...

    These options are used with the -T option and have the same meaning as the corresponding clauses for LOAD DATA INFILE. See Section 12.2.6, “LOAD DATA INFILE Syntax”.

  • --first-slave, -x

    Deprecated. Now renamed to --lock-all-tables.

  • --flush-logs, -F

    Flush the MySQL server log files before starting the dump. This option requires the RELOAD privilege. Note that if you use this option in combination with the --all-databases (or -A) option, the logs are flushed for each database dumped. The exception is when using --lock-all-tables or --master-data: In this case, the logs are flushed only once, corresponding to the moment that all tables are locked. If you want your dump and the log flush to happen at exactly the same moment, you should use --flush-logs together with either --lock-all-tables or --master-data.

  • --flush-privileges

    Emit a FLUSH PRIVILEGES statement after dumping the mysql database. This option should be used any time the dump contains the mysql database and any other database that depends on the data in the mysql database for proper restoration.

  • --force, -f

    Continue even if an SQL error occurs during a table dump.

    One use for this option is to cause mysqldump to continue executing even when it encounters a view that has become invalid because the definition refers to a table that has been dropped. Without --force, mysqldump exits with an error message. With --force, mysqldump prints the error message, but it also writes an SQL comment containing the view definition to the dump output and continues executing.

  • --host=host_name, -h host_name

    Dump data from the MySQL server on the given host. The default host is localhost.

  • --hex-blob

    Dump binary columns using hexadecimal notation (for example, 'abc' becomes 0x616263). The affected data types are BINARY, VARBINARY, BLOB, and BIT.

  • --include-master-host-port

    For the CHANGE MASTER TO statement in a slave dump produced with the --dump-slave option, add MASTER_PORT and MASTER_PORT options for the host name and TCP/IP port number of the slave's master. This option was added in MySQL 6.0.4.

  • --ignore-table=db_name.tbl_name

    Do not dump the given table, which must be specified using both the database and table names. To ignore multiple tables, use this option multiple times. This option also can be used to ignore views.

  • --insert-ignore

    Write INSERT statements with the IGNORE option.

  • --lines-terminated-by=...

    This option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE. See Section 12.2.6, “LOAD DATA INFILE Syntax”.

  • --lock-all-tables, -x

    Lock all tables across all databases. This is achieved by acquiring a global read lock for the duration of the whole dump. This option automatically turns off --single-transaction and --lock-tables.

  • --lock-tables, -l

    Lock all tables before dumping them. The tables are locked with READ LOCAL to allow concurrent inserts in the case of MyISAM tables. For transactional tables such as InnoDB, --single-transaction is a much better option, because it does not need to lock the tables at all.

    Please note that when dumping multiple databases, --lock-tables locks tables for each database separately. Therefore, this option does not guarantee that the tables in the dump file are logically consistent between databases. Tables in different databases may be dumped in completely different states.

  • --log-error=file_name

    Append warnings and errors to the named file.

  • --master-data[=value]

    Use this option to dump a master replication server to produce a dump file that can be used to set up another server as a slave of the master. It causes the dump output to include a CHANGE MASTER TO statement that indicates the binary log coordinates (file name and position) of the dumped server. These are the master server coordinates from which the slave should start replicating.

    If the option value is 2, the CHANGE MASTER TO statement is written as an SQL comment, and thus is informative only; it has no effect when the dump file is reloaded. If the option value is 1, the statement takes effect when the dump file is reloaded. If the option value is not specified, the default value is 1.

    This option requires the RELOAD privilege and the binary log must be enabled.

    The --master-data option automatically turns off --lock-tables. It also turns on --lock-all-tables, unless --single-transaction also is specified, in which case, a global read lock is acquired only for a short time at the beginning of the dump (see the description for --single-transaction). In all cases, any action on logs happens at the exact moment of the dump.

    It is also possible to set up a slave by dumping an existing slave of the master. To do this, use the --dump-slave option instead.

  • --no-autocommit

    Enclose the INSERT statements for each dumped table within SET autocommit = 0 and COMMIT statements.

  • --no-create-db, -n

    This option suppresses the CREATE DATABASE statements that are otherwise included in the output if the --databases or --all-databases option is given.

  • --no-create-info, -t

    Do not write CREATE TABLE statements that re-create each dumped table.

  • --no-data, -d

    Do not write any table row information (that is, do not dump table contents). This is very useful if you want to dump only the CREATE TABLE statement for the table.

  • --no-set-names

    This option is deprecated. Use --skip-set-charset. instead.

  • --opt

    This option is shorthand; it is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. It should give you a fast dump operation and produce a dump file that can be reloaded into a MySQL server quickly.

    The --opt option is enabled by default. Use --skip-opt to disable it. See the discussion at the beginning of this section for information about selectively enabling or disabling certain of the options affected by --opt.

  • --order-by-primary

    Sort each table's rows by its primary key, or by its first unique index, if such an index exists. This is useful when dumping a MyISAM table to be loaded into an InnoDB table, but will make the dump itself take considerably longer.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --pipe, -W

    On Windows, connect to the server via a named pipe. This option applies only for connections to a local server, and only if the server supports named-pipe connections.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for the connection.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the allowable values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --quick, -q

    This option is useful for dumping large tables. It forces mysqldump to retrieve rows for a table from the server a row at a time rather than retrieving the entire row set and buffering it in memory before writing it out.

  • --quote-names, -Q

    Quote database, table, and column names within “`” characters. If the ANSI_QUOTES SQL mode is enabled, names are quoted within “"” characters. This option is enabled by default. It can be disabled with --skip-quote-names, but this option should be given after any option such as --compatible that may enable --quote-names.

  • --replace

    Write REPLACE statements rather than INSERT statements.

  • --result-file=file_name, -r file_name

    Direct output to a given file. This option should be used on Windows to prevent newline “\n” characters from being converted to “\r\n” carriage return/newline sequences. The result file is created and its contents overwritten, even if an error occurs while generating the dump. The previous contents are lost.

  • --routines, -R

    Dump stored routines (procedures and functions) from the dumped databases. Use of this option requires the SELECT privilege for the mysql.proc table. The output generated by using --routines contains CREATE PROCEDURE and CREATE FUNCTION statements to re-create the routines. However, these statements do not include attributes such as the routine creation and modification timestamps. This means that when the routines are reloaded, they will be created with the timestamps equal to the reload time.

    If you require routines to be re-created with their original timestamp attributes, do not use --routines. Instead, dump and reload the contents of the mysql.proc table directly, using a MySQL account that has appropriate privileges for the mysql database.

  • --set-charset

    Add SET NAMES default_character_set to the output. This option is enabled by default. To suppress the SET NAMES statement, use --skip-set-charset.

  • --single-transaction

    This option issues a BEGIN SQL statement before dumping data from the server. It is useful only with transactional tables such as InnoDB, because then it dumps the consistent state of the database at the time when BEGIN was issued without blocking any applications.

    When using this option, you should keep in mind that only InnoDB and Falcon tables are dumped in a consistent state. For example, any MyISAM or MEMORY tables dumped while using this option may still change state.

    While a --single-transaction dump is in process, to ensure a valid dump file (correct table contents and binary log position), no other connection should use the following statements: ALTER TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE. A consistent read is not isolated from those statements, so use of them on a table to be dumped can cause the SELECT performed by mysqldump to retrieve the table contents to obtain incorrect contents or fail.

    The --single-transaction option and the --lock-tables option are mutually exclusive, because LOCK TABLES causes any pending transactions to be committed implicitly.

    To dump large tables, you should combine this option with --quick.

  • --skip-comments

    See the description for the --comments option.

  • --skip-opt

    See the description for the --opt option.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --ssl*

    Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section 5.5.7.3, “SSL Command Options”.

  • --tab=path, -T path

    Produce tab-separated data files. For each dumped table, mysqldump creates a tbl_name.sql file that contains the CREATE TABLE statement that creates the table, and a tbl_name.txt file that contains its data. The option value is the directory in which to write the files.

    By default, the .txt data files are formatted using tab characters between column values and a newline at the end of each line. The format can be specified explicitly using the --fields-xxx and --lines-terminated-by options.

    Column values are dumped using the binary character set and the --default-character-set option is ignored. In effect, there is no character set conversion. If a table contains columns in several character sets, the output data file will as well and you may not be able to reload the file correctly.

    Note

    This option should be used only when mysqldump is run on the same machine as the mysqld server. You must have the FILE privilege, and the server must have permission to write files in the directory that you specify.

  • --tables

    Override the --databases or -B option. mysqldump regards all name arguments following the option as table names.

  • --triggers

    Dump triggers for each dumped table. This option is enabled by default; disable it with --skip-triggers.

  • --tz-utc

    This option enables TIMESTAMP columns to be dumped and reloaded between servers in different time zones. mysqldump sets its connection time zone to UTC and adds SET TIME_ZONE='+00:00' to the dump file. Without this option, TIMESTAMP columns are dumped and reloaded in the time zones local to the source and destination servers, which can cause the values to change. --tz-utc also protects against changes due to daylight saving time. --tz-utc is enabled by default. To disable it, use --skip-tz-utc.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

  • --verbose, -v

    Verbose mode. Print more information about what the program does.

  • --version, -V

    Display version information and exit.

  • --where='where_condition', -w 'where_condition'

    Dump only rows selected by the given WHERE condition. Quotes around the condition are mandatory if it contains spaces or other characters that are special to your command interpreter.

    Examples:

    --where="user='jimf'"
    -w"userid>1"
    -w"userid<1"
    
  • --xml, -X

    Write dump output as well-formed XML.

    NULL, 'NULL', and Empty Values: For some column named column_name, the NULL value, an empty string, and the string value 'NULL' are distinguished from one another in the output generated by this option as follows.

    Value:XML Representation:
    NULL (unknown value)

    <field name="column_name" xsi:nil="true" />

    '' (empty string)

    <field name="column_name"></field>

    'NULL' (string value)

    <field name="column_name">NULL</field>

    The output from the mysql client when run using the --xml option also follows these rules. (See Section 4.5.1.1, “mysql Options”.)

    XML output from mysqldump includes the XML namespace, as shown here:

    shell> mysqldump --xml -u root world City
    <?xml version="1.0"?>
    <mysqldump xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <database name="world">
    <table_structure name="City">
    <field Field="ID" Type="int(11)" Null="NO" Key="PRI" Extra="auto_increment" />
    <field Field="Name" Type="char(35)" Null="NO" Key="" Default="" Extra="" />
    <field Field="CountryCode" Type="char(3)" Null="NO" Key="" Default="" Extra="" />
    <field Field="District" Type="char(20)" Null="NO" Key="" Default="" Extra="" />
    <field Field="Population" Type="int(11)" Null="NO" Key="" Default="0" Extra="" />
    <key Table="City" Non_unique="0" Key_name="PRIMARY" Seq_in_index="1" Column_name="ID" Collation="A" Cardinality="4079"
    Null="" Index_type="BTREE" Comment="" />
    <options Name="City" Engine="MyISAM" Version="10" Row_format="Fixed" Rows="4079" Avg_row_length="67" Data_length="27329
    3" Max_data_length="18858823439613951" Index_length="43008" Data_free="0" Auto_increment="4080" Create_time="2007-03-31 01:47:01" Updat
    e_time="2007-03-31 01:47:02" Collation="latin1_swedish_ci" Create_options="" Comment="" />
    </table_structure>
    <table_data name="City">
    <row>
    <field name="ID">1</field>
    <field name="Name">Kabul</field>
    <field name="CountryCode">AFG</field>
    <field name="District">Kabol</field>
    <field name="Population">1780000</field>
    </row>
    
    ...
    
    <row>
    <field name="ID">4079</field>
    <field name="Name">Rafah</field>
    <field name="CountryCode">PSE</field>
    <field name="District">Rafah</field>
    <field name="Population">92020</field>
    </row>
    </table_data>
    </database>
    </mysqldump>
    

You can also set the following variables by using --var_name=value syntax:

  • max_allowed_packet

    The maximum size of the buffer for client/server communication. The maximum is 1GB.

  • net_buffer_length

    The initial size of the buffer for client/server communication. When creating multiple-row-insert statements (as with option --extended-insert or --opt), mysqldump creates rows up to net_buffer_length length. If you increase this variable, you should also ensure that the net_buffer_length variable in the MySQL server is at least this large.

The most common use of mysqldump is probably for making a backup of an entire database:

shell> mysqldump db_name > backup-file.sql

You can read the dump file back into the server like this:

shell> mysql db_name < backup-file.sql

Or like this:

shell> mysql -e "source /path-to-backup/backup-file.sql" db_name

mysqldump is also very useful for populating databases by copying data from one MySQL server to another:

shell> mysqldump --opt db_name | mysql --host=remote_host -C db_name

It is possible to dump several databases with one command:

shell> mysqldump --databases db_name1 [db_name2 ...] > my_databases.sql

To dump all databases, use the --all-databases option:

shell> mysqldump --all-databases > all_databases.sql

For InnoDB tables, mysqldump provides a way of making an online backup:

shell> mysqldump --all-databases --single-transaction > all_databases.sql

This backup acquires a global read lock on all tables (using FLUSH TABLES WITH READ LOCK) at the beginning of the dump. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released. If long updating statements are running when the FLUSH statement is issued, the MySQL server may get stalled until those statements finish. After that, the dump becomes lock-free and does not disturb reads and writes on the tables. If the update statements that the MySQL server receives are short (in terms of execution time), the initial lock period should not be noticeable, even with many updates.

For point-in-time recovery (also known as “roll-forward,” when you need to restore an old backup and replay the changes that happened since that backup), it is often useful to rotate the binary log (see Section 5.2.4, “The Binary Log”) or at least know the binary log coordinates to which the dump corresponds:

shell> mysqldump --all-databases --master-data=2 > all_databases.sql

Or:

shell> mysqldump --all-databases --flush-logs --master-data=2
              > all_databases.sql

The --master-data and --single-transaction options can be used simultaneously, which provides a convenient way to make an online backup suitable for point-in-time recovery if tables are stored using the InnoDB storage engine.

For more information on making backups, see Section 6.1, “Database Backups”, and Section 6.2, “Example Backup and Recovery Strategy”.

If you encounter problems backing up views, please read the section that covers restrictions on views which describes a workaround for backing up views when this fails due to insufficient privileges. See Section D.5, “Restrictions on Views”.

MySQL Enterprise MySQL Enterprise subscribers will find more information about mysqldump in the Knowledge Base article, How Can I Avoid Inserting Duplicate Rows From a Dump File?. Access to the MySQL Knowledge Base collection of articles is one of the advantages of subscribing to MySQL Enterprise. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

4.5.5. mysqlimport — A Data Import Program

The mysqlimport client provides a command-line interface to the LOAD DATA INFILE SQL statement. Most options to mysqlimport correspond directly to clauses of LOAD DATA INFILE syntax. See Section 12.2.6, “LOAD DATA INFILE Syntax”.

Invoke mysqlimport like this:

shell> mysqlimport [options] db_name textfile1 [textfile2 ...]

For each text file named on the command line, mysqlimport strips any extension from the file name and uses the result to determine the name of the table into which to import the file's contents. For example, files named patient.txt, patient.text, and patient all would be imported into a table named patient.

Table 4.6. mysqlimport Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--columns=column_listcolumnsThis option takes a comma-separated list of column names as its value   
--compresscompressCompress all information sent between the client and the server   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--deletedeleteEmpty the table before importing the text file   
--fields-enclosed-by=stringfields-enclosed-byThis option has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-escaped-byfields-escaped-byThis option has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-optionally-enclosed-by=stringfields-optionally-enclosed-byThis option has the same meaning as the corresponding clause for LOAD DATA INFILE   
--fields-terminated-by=stringfields-terminated-by-- This option has the same meaning as the corresponding clause for LOAD DATA INFILE   
--forceforceContinue even if an SQL error occurs   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--ignoreignoreSee the description for the --replace option   
--ignore-lines=#ignore-linesIgnore the first N lines of the data file   
--lines-terminated-by=stringlines-terminated-byThis option has the same meaning as the corresponding clause for LOAD DATA INFILE   
--locallocalRead input files locally from the client host   
--lock-tableslock-tablesLock all tables for writing before processing any text files   
--low-prioritylow-priorityUse LOW_PRIORITY when loading the table.   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server via a named pipe   
--port=port_numportThe TCP/IP port number to use for the connection   
--protocol=typeprotocolThe connection protocol to use   
--replacereplaceThe --replace and --ignore options control handling of input rows that duplicate existing rows on unique key values   
--silentsilentProduce output only when errors occur   
--socket=pathsocketFor connections to localhost   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--use-threads=#use-threadsThe number of threads for parallel file-loading   
--user=user_name,userThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   

mysqlimport supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

Here is a sample session that demonstrates use of mysqlimport:

shell> mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test
shell> ed
a
100     Max Sydow
101     Count Dracula
.
w imptest.txt
32
q
shell> od -c imptest.txt
0000000   1   0   0  \t   M   a   x       S   y   d   o   w  \n   1   0
0000020   1  \t   C   o   u   n   t       D   r   a   c   u   l   a  \n
0000040
shell> mysqlimport --local test imptest.txt
test.imptest: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0
shell> mysql -e 'SELECT * FROM imptest' test
+------+---------------+
| id   | n             |
+------+---------------+
|  100 | Max Sydow     |
|  101 | Count Dracula |
+------+---------------+

4.5.6. mysqlshow — Display Database, Table, and Column Information

The mysqlshow client can be used to quickly see which databases exist, their tables, or a table's columns or indexes.

mysqlshow provides a command-line interface to several SQL SHOW statements. See Section 12.5.6, “SHOW Syntax”. The same information can be obtained by using those statements directly. For example, you can issue them from the mysql client program.

Invoke mysqlshow like this:

shell> mysqlshow [options] [db_name [tbl_name [col_name]]]
  • If no database is given, a list of database names is shown.

  • If no table is given, all matching tables in the database are shown.

  • If no column is given, all matching columns and column types in the table are shown.

The output displays only the names of those databases, tables, or columns for which you have some privileges.

If the last argument contains shell or SQL wildcard characters (“*”, “?”, “%”, or “_”), only those names that are matched by the wildcard are shown. If a database name contains any underscores, those should be escaped with a backslash (some Unix shells require two) to get a list of the proper tables or columns. “*” and “?” characters are converted into SQL “%” and “_” wildcard characters. This might cause some confusion when you try to display the columns for a table with a “_” in the name, because in this case, mysqlshow shows you only the table names that match the pattern. This is easily fixed by adding an extra “%” last on the command line as a separate argument.

Table 4.7. mysqlshow Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--compresscompressCompress all information sent between the client and the server   
--countcountShow the number of rows per table   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--default-character-set=charset_namedefault-character-setUse charset_name as the default character set   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--keyskeysShow table indexes   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server via a named pipe   
--port=port_numportThe TCP/IP port number to use for the connection   
--protocol=typeprotocolThe connection protocol to use   
--show-table-type Show a column indicating the table type   
--socket=pathsocketFor connections to localhost   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--statusstatusDisplay extra information about each table   
--user=user_name,userThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   

mysqlshow supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

4.5.7. mysqlslap — Load Emulation Client

mysqlslap is a diagnostic program designed to emulate client load for a MySQL server and to report the timing of each stage. It works as if multiple clients are accessing the server.

Invoke mysqlslap like this:

shell> mysqlslap [options]

Some options such as --create or --query enable you to specify a string containing an SQL statement or a file containing statements. If you specify a file, by default it must contain one statement per line. (That is, the implicit statement delimiter is the newline character.) Use the --delimiter option to specify a different delimiter, which enables you to specify statements that span multiple lines or place multiple statements on a single line. You cannot include comments in a file; mysqlslap does not understand them.

mysqlslap runs in three stages:

  1. Create schema, table, and optionally any stored programs or data you want to using for the test. This stage uses a single client connection.

  2. Run the load test. This stage can use many client connections.

  3. Clean up (disconnect, drop table if specified). This stage uses a single client connection.

Examples:

Supply your own create and query SQL statements, with 50 clients querying and 200 selects for each:

mysqlslap --delimiter=";" \
  --create="CREATE TABLE a (b int);INSERT INTO a VALUES (23)" \
  --query="SELECT * FROM a" --concurrency=50 --iterations=200

Let mysqlslap build the query SQL statement with a table of two INT columns and three VARCHAR columns. Use five clients querying 20 times each. Do not create the table or insert the data (that is, use the previous test's schema and data):

mysqlslap --concurrency=5 --iterations=20 \
  --number-int-cols=2 --number-char-cols=3 \
  --auto-generate-sql

Tell the program to load the create, insert, and query SQL statements from the specified files, where the create.sql file has multiple table creation statements delimited by ';' and multiple insert statements delimited by ';'. The --query file will have multiple queries delimited by ';'. Run all the load statements, then run all the queries in the query file with five clients (five times each):

mysqlslap --concurrency=5 \
  --iterations=5 --query=query.sql --create=create.sql \
  --delimiter=";"

Table 4.8. mysqlslap Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--auto-generate-sqlauto-generate-sqlGenerate SQL statements automatically when they are not supplied in files or via command options   
--auto-generate-sql-add-autoincrementauto-generate-sql-add-autoincrementAdd AUTO_INCREMENT column to automatically generated tables   
--auto-generate-sql-execute-number=#auto-generate-sql-execute-numberSpecify how many queries to generate automatically   
--auto-generate-sql-guid-primaryauto-generate-sql-guid-primaryAdd a GUID-based primary key to automatically generated tables   
--auto-generate-sql-load-type=typeauto-generate-sql-load-typeSpecify how many queries to generate automatically   
--auto-generate-sql-secondary-indexes=#auto-generate-sql-secondary-indexesSpecify how many secondary indexes to add to automatically generated tables   
--auto-generate-sql-select-columns=strauto-generate-sql-select-columnsThe string to use for the select columns used in automatic tests6.0.3  
--auto-generate-sql-unique-query-number=#auto-generate-sql-unique-query-numberHow many different queries to generate for automatic tests.   
--auto-generate-sql-unique-write-number=#auto-generate-sql-unique-write-numberHow many different queries to generate for --auto-generate-sql-write-number   
--auto-generate-sql-write-number=#auto-generate-sql-write-numberHow many row inserts to perform on each thread   
--burninburninRun the full test case in an infinite loop6.0.3  
--commit=#commitHow many statements to execute before committing.   
--compresscompressCompress all information sent between the client and the server   
--concurrency=#concurrencyThe number of clients to simulate when issuing the SELECT statement   
--create=valuecreateThe file or string containing the statement to use for creating the table   
--create-schema=valuecreate-schemaThe schema in which to run the tests   
--csv=[file]csvGenerate output in comma-separated values format   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--delayed-start=#delayed-startDelay each thread start by random number of microseconds up to this maximum6.0.3  
--delimiter=strdelimiterThe delimiter to use in SQL statements   
--detach=#detachDetach (close and reopen) each connection after each N statements   
--engine=engine_nameengineThe storage engine to use for creating the table   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--ignore-sql-errorsignore-sql-errorsIgnore SQL errors during the test run6.0.4  
--iterations=#iterationsThe number of times to run the tests   
--label=strlabelThe label to use in SQL statements6.0.3  
--number-blob-cols=#number-blob-colsThe number of BLOB columns to use if --auto-generate-sql is specified6.0.3  
--number-char-cols=#number-char-colsThe number of VARCHAR columns to use if --auto-generate-sql is specified   
--number-int-cols=#number-int-colsThe number of INT columns to use if --auto-generate-sql is specified   
--number-of-queries=#number-of-queriesLimit each client to approximately this number of queries   
--only-printonly-printDo not connect to databases. mysqlslap only prints what it would have done   
--password[=password]passwordThe password to use when connecting to the server   
--pipe On Windows, connect to server via a named pipe   
--port=port_numportThe TCP/IP port number to use for the connection   
--post-query=valuepost-queryThe file or string containing the statement to execute after the tests have completed   
--post-system=strpost-systemThe string to execute via system() after the tests have completed   
--pre-query=valuepre-queryThe file or string containing the statement to execute before running the tests   
--pre-system=strpre-systemThe string to execute via system()> before running the tests   
--preserve-schemapreserve-schemaPreserve the schema from the mysqlslap run  6.0.5
--protocol=typeprotocolThe connection protocol to use   
--query=valuequeryThe file or string containg the SELECT statement to use for retrieving data   
--set-random-seed=#set-random-seedThe seed value for the randomizer   
--silentsilentSilent mode   
--socket=pathsocketFor connections to localhost   
--ssl-ca=file_namessl-caThe path to a file that contains a list of trusted SSL CAs   
--ssl-capath=directory_namessl-capathThe path to a directory that contains trusted SSL CA certificates in PEM format   
--ssl-cert=file_namessl-certThe name of the SSL certificate file to use for establishing a secure connection   
--ssl-cipher=cipher_listssl-cipherA list of allowable ciphers to use for SSL encryption   
--ssl-key=file_namessl-keyThe name of the SSL key file to use for establishing a secure connection   
--ssl-verify-server-certssl-verify-server-certThe server's Common Name value in its certificate is verified against the host name used when connecting to the server   
--timer-length=#timer-lengthThe duration in seconds to run each test6.0.3  
--user=user_name,userThe MySQL user name to use when connecting to the server   
--verbose Verbose mode   
--version Display version information and exit   

mysqlslap supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help, -?

    Display a help message and exit.

  • --auto-generate-sql, -a

    Generate SQL statements automatically when they are not supplied in files or via command options.

  • --auto-generate-sql-add-autoincrement

    Add an AUTO_INCREMENT column to automatically generated tables.

  • --auto-generate-sql-execute-number=N

    Specify how many queries to generate automatically.

  • --auto-generate-sql-guid-primary

    Add a GUID-based primary key to automatically generated tables.

  • --auto-generate-sql-load-type=type

    Specify the test load type. The allowable values are read (scan tables), write (insert into tables), key (read primary keys), update (update primary keys), or mixed (half inserts, half scanning selects). The default is mixed.

  • --auto-generate-sql-secondary-indexes=N

    Specify how many secondary indexes to add to automatically generated tables. By default, none are added.

  • --auto-generate-sql-select-columns=str

    The string to use for the select columns used in automatic tests. You can use this to determine the effect on performance of selecting or excluding particular columns. This option was added in MySQL 6.0.3.

  • --auto-generate-sql-unique-query-number=N

    How many different queries to generate for automatic tests. For example, if you run a key test that performs 1000 selects, you can use this option with a value of 1000 to run 1000 unique queries, or with a value of 50 to perform 50 different selects. The default is 10.

  • --auto-generate-sql-unique-write-number=N

    How many different queries to generate for --auto-generate-sql-write-number. The default is 10.

  • --auto-generate-sql-write-number=N

    How many row inserts to perform on each thread. The default is 100.

  • --burnin

    Run the full test case in an infinite loop. This option was added in MySQL 6.0.3.

  • --commit=N

    How many statements to execute before committing. The default is 0 (no commits are done).

  • --compress, -C

    Compress all information sent between the client and the server if both support compression.

  • --concurrency=N, -c N

    The number of clients to simulate when issuing the SELECT statement.

  • --create=value

    The file or string containing the statement to use for creating the table.

  • --create-schema=value

    The schema in which to run the tests.

  • --csv[=file_name]

    Generate output in comma-separated values format. The output goes to the named file, or to the standard output if no file is given.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysqlslap.trace'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info, -T

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --delimiter=str, -F str

    The delimiter to use in SQL statements supplied in files or via command options.

  • --delayed-start=N

    The maximum delay in microseconds. Startup of each thread is delayed by a random number of microseconds up to this maximum. The default is 0. This option was added in MySQL 6.0.3.

  • --detach=N

    Detach (close and reopen) each connection after each N statements. The default is 0 (connections are not detached).

  • --engine=engine_name, -e engine_name

    The storage engine to use for creating tables.

  • --host=host_name, -h host_name

    Connect to the MySQL server on the given host.

  • --ignore-sql-errors

    Ignore SQL errors during the test run. By default, errors cause mysqlslap to exit. This option was added in MySQL 6.0.4.

  • --iterations=N, -i N

    The number of times to run the tests.

  • --label=str

    The label to use in printed and CSV output. This option was added in MySQL 6.0.3.

  • --number-blob-cols=str,

    The number of BLOB columns to use if --auto-generate-sql is specified. --number-blob-cols=3:1024/2048 would give you 3 BLOB columns with a random size between 1024 and 2048. This option was added in MySQL 6.0.3.

  • --number-char-cols=N, -x N

    The number of VARCHAR columns to use if --auto-generate-sql is specified.

  • --number-int-cols=N, -y N

    The number of INT columns to use if --auto-generate-sql is specified.

  • --number-of-queries=N

    Limit each client to approximately this number of queries.

  • --only-print

    Do not connect to databases. mysqlslap only prints what it would have done.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --pipe, -W

    On Windows, connect to the server via a named pipe. This option applies only for connections to a local server, and only if the server supports named-pipe connections.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for the connection.

  • --post-query=value

    The file or string containing the statement to execute after the tests have completed. This execution is not counted for timing purposes.

  • --shared-memory-base-name=name

    On Windows, the shared-memory name to use, for connections made via shared memory to a local server. This option applies only if the server supports shared-memory connections.

  • --post-system=str

    The string to execute via system() after the tests have completed. This execution is not counted for timing purposes.

  • --pre-query=value

    The file or string containing the statement to execute before running the tests. This execution is not counted for timing purposes. This option was added in MySQL 5.1.18.

  • --pre-system=str

    The string to execute via system() before running the tests. This execution is not counted for timing purposes.

  • --preserve-schema

    Preserve the schema from the mysqlslap run. The --auto-generate-sql and --create options disable this option. This option was removed in MySQL 6.0.5.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the allowable values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --query=value, -q value

    The file or string containing the SELECT statement to use for retrieving data.

  • --set-random-seed=value,

    The seed value for the randomizer.

  • --silent, -s

    Silent mode. No output.

  • --slave

    Follow master locks for other mysqlslap clients. Use this option if you are trying to synchronize around one master server with --lock-directory plus NFS.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --ssl*

    Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section 5.5.7.3, “SSL Command Options”.

  • --timer-length=N

    The duration in seconds to run each test. Tests that run longer are terminated. This option was added in MySQL 6.0.3.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

  • --verbose, -v

    Verbose mode. Print more information about what the program does. This option can be used multiple times to increase the amount of information.

  • --version, -V

    Display version information and exit.

4.6. MySQL Administrative and Utility Programs

This section describes administrative programs and programs that perform miscellaneous utility operations.

4.6.1. innochecksum — Offline InnoDB File Checksum Utility

innochecksum prints checksums for InnoDB files.

Invoke innochecksum like this:

shell> innochecksum [options] file_name

innochecksum supports the options described in the following list. For options that refer to page numbers, the numbers are zero-based.

  • -c

    Print a count of the number of pages in the file.

  • -d

    Debug mode; prints checksums for each page.

  • -e num

    End at this page number.

  • -p num

    Check only this page number.

  • -s num

    Start at this page number.

  • -v

    Verbose mode; print a progress indicator every five seconds.

4.6.2. myisam_ftdump — Display Full-Text Index information

myisam_ftdump displays information about FULLTEXT indexes in MyISAM tables. It reads the MyISAM index file directly, so it must be run on the server host where the table is located

Invoke myisam_ftdump like this:

shell> myisam_ftdump [options] tbl_name index_num

The tbl_name argument should be the name of a MyISAM table. You can also specify a table by naming its index file (the file with the .MYI suffix). If you do not invoke myisam_ftdump in the directory where the table files are located, the table or index file name must be preceded by the path name to the table's database directory. Index numbers begin with 0.

Example: Suppose that the test database contains a table named mytexttablel that has the following definition:

CREATE TABLE mytexttable
(
  id   INT NOT NULL,
  txt  TEXT NOT NULL,
  PRIMARY KEY (id),
  FULLTEXT (txt)
);

The index on id is index 0 and the FULLTEXT index on txt is index 1. If your working directory is the test database directory, invoke myisam_ftdump as follows:

shell> myisam_ftdump mytexttable 1

If the path name to the test database directory is /usr/local/mysql/data/test, you can also specify the table name argument using that path name. This is useful if you do not invoke myisam_ftdump in the database directory:

shell> myisam_ftdump /usr/local/mysql/data/test/mytexttable 1

myisam_ftdump supports the following options:

  • --help, -h -?

    Display a help message and exit.

  • --count, -c

    Calculate per-word statistics (counts and global weights).

  • --dump, -d

    Dump the index, including data offsets and word weights.

  • --length, -l

    Report the length distribution.

  • --stats, -s

    Report global index statistics. This is the default operation if no other operation is specified.

  • --verbose, -v

    Verbose mode. Print more output about what the program does.

4.6.3. myisamchk — MyISAM Table-Maintenance Utility

The myisamchk utility gets information about your database tables or checks, repairs, or optimizes them. myisamchk works with MyISAM tables (tables that have .MYD and .MYI files for storing data and indexes).

The use of myisamchk with partitioned tables is not supported.

Caution

It is best to make a backup of a table before performing a table repair operation; under some circumstances the operation might cause data loss. Possible causes include but are not limited to file system errors.

Invoke myisamchk like this:

shell> myisamchk [options] tbl_name ...

The options specify what you want myisamchk to do. They are described in the following sections. You can also get a list of options by invoking myisamchk --help.

With no options, myisamchk simply checks your table as the default operation. To get more information or to tell myisamchk to take corrective action, specify options as described in the following discussion.

tbl_name is the database table you want to check or repair. If you run myisamchk somewhere other than in the database directory, you must specify the path to the database directory, because myisamchk has no idea where the database is located. In fact, myisamchk does not actually care whether the files you are working on are located in a database directory. You can copy the files that correspond to a database table into some other location and perform recovery operations on them there.

You can name several tables on the myisamchk command line if you wish. You can also specify a table by naming its index file (the file with the .MYI suffix). This allows you to specify all tables in a directory by using the pattern *.MYI. For example, if you are in a database directory, you can check all the MyISAM tables in that directory like this:

shell> myisamchk *.MYI

If you are not in the database directory, you can check all the tables there by specifying the path to the directory:

shell> myisamchk /path/to/database_dir/*.MYI

You can even check all tables in all databases by specifying a wildcard with the path to the MySQL data directory:

shell> myisamchk /path/to/datadir/*/*.MYI

The recommended way to quickly check all MyISAM tables is:

shell> myisamchk --silent --fast /path/to/datadir/*/*.MYI

If you want to check all MyISAM tables and repair any that are corrupted, you can use the following command:

shell> myisamchk --silent --force --fast --update-state \
          --key_buffer_size=64M --sort_buffer_size=64M \
          --read_buffer_size=1M --write_buffer_size=1M \
          /path/to/datadir/*/*.MYI

This command assumes that you have more than 64MB free. For more information about memory allocation with myisamchk, see Section 4.6.3.5, “myisamchk Memory Usage”.

MySQL Enterprise For expert advice on checking and repairing tables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

Important

You must ensure that no other program is using the tables while you are running myisamchk. The most effective means of doing so is to shut down the MySQL server while running myisamchk, or to lock all tables that myisamchk is being used on.

Otherwise, when you run myisamchk, it may display the following error message:

warning: clients are using or haven't closed the table properly

This means that you are trying to check a table that has been updated by another program (such as the mysqld server) that hasn't yet closed the file or that has died without closing the file properly, which can sometimes lead to the corruption of one or more MyISAM tables.

If mysqld is running, you must force it to flush any table modifications that are still buffered in memory by using FLUSH TABLES. You should then ensure that no one is using the tables while you are running myisamchk

However, the easiest way to avoid this problem is to use CHECK TABLE instead of myisamchk to check tables. See Section 12.5.2.2, “CHECK TABLE Syntax”.

myisamchk supports the options in the following table. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

Table 4.9. myisamchk Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--analyzeanalyzeAnalyze the distribution of key values   
--backupbackupMake a backup of the .MYD file as file_name-time.BAK   
--block-search=offsetblock-searchFind the record that a block at the given offset belongs to   
--checkcheckCheck the table for errors   
--check-only-changedcheck-only-changedCheck only tables that have changed since the last check   
--correct-checksumcorrect-checksumCorrect the checksum information for the table   
--data-file-length=lendata-file-lengthMaximum length of the data file (when re-creating data file when it is full)   
--debug[=debug_options]debugWrite a debugging log   
decode_bits=#decode_bitsDecode_bits   
--descriptiondescriptionPrint some descriptive information about the table   
--extend-checkextend-checkDo a repair that tries to recover every possible row from the data file   
--extended-checkextended-checkCheck the table very thoroughly   
--fastfastCheck only tables that haven't been closed properly   
--forceforceDo a repair operation automatically if myisamchk finds any errors in the table   
--forceforce-recoverOverwrite old temporary files. For use with the -r or -o option   
ft_max_word_len=#ft_max_word_lenMaximum word length for FULLTEXT indexes   
ft_min_word_len=#ft_min_word_lenMinimum word length for FULLTEXT indexes   
ft_stopword_file=valueft_stopword_fileUse stopwords from this file instead of built-in list   
--HELP Display help message and exit   
--help Display help message and exit   
--informationinformationPrint informational statistics about the table that is checked   
key_buffer_size=#key_buffer_sizeThe size of the buffer used for index blocks for MyISAM tables   
--keys-used=valkeys-usedA bit-value that indicates which indexes to update   
--max-record-length=lenmax-record-lengthSkip rows larger than the given length if myisamchk cannot allocate memory to hold them   
--medium-checkmedium-checkDo a check that is faster than an --extend-check operation   
myisam_block_size=#myisam_block_sizeBlock size to be used for MyISAM index pages   
--parallel-recoverparallel-recoverUses the same technique as -r and -n, but creates all the keys in parallel, using different threads (beta)   
--quickquickAchieve a faster repair by not modifying the data file.   
read_buffer_size=#read_buffer_sizeEach thread that does a sequential scan allocates a buffer of this size for each table it scans   
--read-onlyread-onlyDon't mark the table as checked   
--recoverrecoverDo a repair that can fix almost any problem except unique keys that aren't unique   
--safe-recoversafe-recoverDo a repair using an old recovery method that reads through all rows in order and updates all index trees based on the rows found   
--set-auto-increment[=value]set-auto-incrementForce AUTO_INCREMENT numbering for new records to start at the given value   
--set-collation=nameset-collationSpecify the collation to use for sorting table indexes   
--silentsilentSilent mode   
sort_buffer_size=#sort_buffer_sizeThe buffer that is allocated when sorting the index when doing a REPAIR or when creating indexes with CREATE INDEX or ALTER TABLE   
--sort-indexsort-indexSort the index tree blocks in high-low order   
sort_key_blocks=#sort_key_blockssort_key_blocks   
--sort-records=#sort-recordsSort records according to a particular index   
--sort-recoversort-recoverForce myisamchk to use sorting to resolve the keys even if the temporary files would be very large   
stats_method=valuestats_methodSpecifies how MyISAM index statistics collection code should treat NULLs   
--tmpdir=pathtmpdirPath of the directory to be used for storing temporary files   
--unpackunpackUnpack a table that was packed with myisampack   
--update-stateupdate-stateStore information in the .MYI file to indicate when the table was checked and whether the table crashed   
--verbose Verbose mode   
--version Display version information and exit   
write_buffer_size=#write_buffer_sizeWrite buffer size   

4.6.3.1. myisamchk General Options

The options described in this section can be used for any type of table maintenance operation performed by myisamchk. The sections following this one describe options that pertain only to specific operations, such as table checking or repairing.

  • --help, -?

    Display a help message and exit. Options are grouped by type of operation.

  • --HELP, -H

    Display a help message and exit. Options are presented in a single list.

  • --debug=debug_options, -# debug_options

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/myisamchk.trace'.

  • --silent, -s

    Silent mode. Write output only when errors occur. You can use -s twice (-ss) to make myisamchk very silent.

  • --verbose, -v

    Verbose mode. Print more information about what the program does. This can be used with -d and -e. Use -v multiple times (-vv, -vvv) for even more output.

  • --version, -V

    Display version information and exit.

  • --wait, -w

    Instead of terminating with an error if the table is locked, wait until the table is unlocked before continuing. If you are running mysqld with external locking disabled, the table can be locked only by another myisamchk command.

You can also set the following variables by using --var_name=value syntax:

VariableDefault Value
decode_bits9
ft_max_word_lenversion-dependent
ft_min_word_len4
ft_stopword_filebuilt-in list
key_buffer_size523264
myisam_block_size1024
read_buffer_size262136
sort_buffer_size2097144
sort_key_blocks16
stats_methodnulls_unequal
write_buffer_size262136

The possible myisamchk variables and their default values can be examined with myisamchk --help:

sort_buffer_size is used when the keys are repaired by sorting keys, which is the normal case when you use --recover.

key_buffer_size is used when you are checking the table with --extend-check or when the keys are repaired by inserting keys row by row into the table (like when doing normal inserts). Repairing through the key buffer is used in the following cases:

  • You use --safe-recover.

  • The temporary files needed to sort the keys would be more than twice as big as when creating the key file directly. This is often the case when you have large key values for CHAR, VARCHAR, or TEXT columns, because the sort operation needs to store the complete key values as it proceeds. If you have lots of temporary space and you can force myisamchk to repair by sorting, you can use the --sort-recover option.

Repairing through the key buffer takes much less disk space than using sorting, but is also much slower.

If you want a faster repair, set the key_buffer_size and sort_buffer_size variables to about 25% of your available memory. You can set both variables to large values, because only one of them is used at a time.

myisam_block_size is the size used for index blocks.

stats_method influences how NULL values are treated for index statistics collection when the --analyze option is given. It acts like the myisam_stats_method system variable. For more information, see the description of myisam_stats_method in Section 5.1.4, “Server System Variables”, and Section 7.4.6, “MyISAM Index Statistics Collection”. For MySQL 6.0, stats_method was added in MySQL 5.0.14. For older versions, the statistics collection method is equivalent to nulls_equal.

The ft_min_word_len and ft_max_word_len variables are available as of MySQL 4.0.0. ft_stopword_file is available as of MySQL 4.0.19.

ft_min_word_len and ft_max_word_len indicate the minimum and maximum word length for FULLTEXT indexes. ft_stopword_file names the stopword file. These need to be set under the following circumstances.

If you use myisamchk to perform an operation that modifies table indexes (such as repair or analyze), the FULLTEXT indexes are rebuilt using the default full-text parameter values for minimum and maximum word length and the stopword file unless you specify otherwise. This can result in queries failing.

The problem occurs because these parameters are known only by the server. They are not stored in MyISAM index files. To avoid the problem if you have modified the minimum or maximum word length or the stopword file in the server, specify the same ft_min_word_len, ft_max_word_len, and ft_stopword_file values to myisamchk that you use for mysqld. For example, if you have set the minimum word length to 3, you can repair a table with myisamchk like this:

shell> myisamchk --recover --ft_min_word_len=3 tbl_name.MYI

To ensure that myisamchk and the server use the same values for full-text parameters, you can place each one in both the [mysqld] and [myisamchk] sections of an option file:

[mysqld]
ft_min_word_len=3

[myisamchk]
ft_min_word_len=3

An alternative to using myisamchk is to use the REPAIR TABLE, ANALYZE TABLE, OPTIMIZE TABLE, or ALTER TABLE. These statements are performed by the server, which knows the proper full-text parameter values to use.

4.6.3.2. myisamchk Check Options

myisamchk supports the following options for table checking operations:

  • --check, -c

    Check the table for errors. This is the default operation if you specify no option that selects an operation type explicitly.

  • --check-only-changed, -C

    Check only tables that have changed since the last check.

  • --extend-check, -e

    Check the table very thoroughly. This is quite slow if the table has many indexes. This option should only be used in extreme cases. Normally, myisamchk or myisamchk --medium-check should be able to determine whether there are any errors in the table.

    If you are using --extend-check and have plenty of memory, setting the key_buffer_size variable to a large value helps the repair operation run faster.

  • --fast, -F

    Check only tables that haven't been closed properly.

  • --force, -f

    Do a repair operation automatically if myisamchk finds any errors in the table. The repair type is the same as that specified with the --recover or -r option.

  • --information, -i

    Print informational statistics about the table that is checked.

  • --medium-check, -m

    Do a check that is faster than an --extend-check operation. This finds only 99.99% of all errors, which should be good enough in most cases.

  • --read-only, -T

    Do not mark the table as checked. This is useful if you use myisamchk to check a table that is in use by some other application that does not use locking, such as mysqld when run with external locking disabled.

  • --update-state, -U

    Store information in the .MYI file to indicate when the table was checked and whether the table crashed. This should be used to get full benefit of the --check-only-changed option, but you shouldn't use this option if the mysqld server is using the table and you are running it with external locking disabled.

4.6.3.3. myisamchk Repair Options

myisamchk supports the following options for table repair operations:

  • --backup, -B

    Make a backup of the .MYD file as file_name-time.BAK

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --correct-checksum

    Correct the checksum information for the table.

  • --data-file-length=len, -D len

    The maximum length of the data file (when re-creating data file when it is “full”).

  • --extend-check, -e

    Do a repair that tries to recover every possible row from the data file. Normally, this also finds a lot of garbage rows. Do not use this option unless you are desperate.

  • --force, -f

    Overwrite old intermediate files (files with names like tbl_name.TMD) instead of aborting.

  • --keys-used=val, -k val

    For myisamchk, the option value is a bit-value that indicates which indexes to update. Each binary bit of the option value corresponds to a table index, where the first index is bit 0. An option value of 0 disables updates to all indexes, which can be used to get faster inserts. Deactivated indexes can be reactivated by using myisamchk -r.

  • --no-symlinks, -l

    Do not follow symbolic links. Normally myisamchk repairs the table that a symlink points to. This option does not exist as of MySQL 4.0 because versions from 4.0 on do not remove symlinks during repair operations.

  • --max-record-length=len

    Skip rows larger than the given length if myisamchk cannot allocate memory to hold them.

  • --parallel-recover, -p

    Use the same technique as -r and -n, but create all the keys in parallel, using different threads. This is beta-quality code. Use at your own risk!

  • --quick, -q

    Achieve a faster repair by not modifying the data file. You can specify this option twice to force myisamchk to modify the original data file in case of duplicate keys.

  • --recover, -r

    Do a repair that can fix almost any problem except unique keys that are not unique (which is an extremely unlikely error with MyISAM tables). If you want to recover a table, this is the option to try first. You should try --safe-recover only if myisamchk reports that the table cannot be recovered using --recover. (In the unlikely case that --recover fails, the data file remains intact.)

    If you have lots of memory, you should increase the value of sort_buffer_size.

  • --safe-recover, -o

    Do a repair using an old recovery method that reads through all rows in order and updates all index trees based on the rows found. This is an order of magnitude slower than --recover, but can handle a couple of very unlikely cases that --recover cannot. This recovery method also uses much less disk space than --recover. Normally, you should repair first using --recover, and then with --safe-recover only if --recover fails.

    If you have lots of memory, you should increase the value of key_buffer_size.

  • --set-character-set=name

    Change the character set used by the table indexes. This option was replaced by --set-collation in MySQL 5.0.3.

  • --set-collation=name

    Specify the collation to use for sorting table indexes. The character set name is implied by the first part of the collation name.

  • --sort-recover, -n

    Force myisamchk to use sorting to resolve the keys even if the temporary files would be very large.

  • --tmpdir=path, -t path

    The path of the directory to be used for storing temporary files. If this is not set, myisamchk uses the value of the TMPDIR environment variable. tmpdir can be set to a list of directory paths that are used successively in round-robin fashion for creating temporary files. The separator character between directory names is the colon (“:”) on Unix and the semicolon (“;”) on Windows, NetWare, and OS/2.

  • --unpack, -u

    Unpack a table that was packed with myisampack.

4.6.3.4. Other myisamchk Options

myisamchk supports the following options for actions other than table checks and repairs:

  • --analyze, -a

    Analyze the distribution of key values. This improves join performance by enabling the join optimizer to better choose the order in which to join the tables and which indexes it should use. To obtain information about the key distribution, use a myisamchk --description --verbose tbl_name command or the SHOW INDEX FROM tbl_name statement.

    MySQL Enterprise For expert advice on optimizing tables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

  • --block-search=offset, -b offset

    Find the record that a block at the given offset belongs to.

  • --description, -d

    Print some descriptive information about the table.

  • --set-auto-increment[=value], -A[value]

    Force AUTO_INCREMENT numbering for new records to start at the given value (or higher, if there are existing records with AUTO_INCREMENT values this large). If value is not specified, AUTO_INCREMENT numbers for new records begin with the largest value currently in the table, plus one.

  • --sort-index, -S

    Sort the index tree blocks in high-low order. This optimizes seeks and makes table scans that use indexes faster.

  • --sort-records=N, -R N

    Sort records according to a particular index. This makes your data much more localized and may speed up range-based SELECT and ORDER BY operations that use this index. (The first time you use this option to sort a table, it may be very slow.) To determine a table's index numbers, use SHOW INDEX, which displays a table's indexes in the same order that myisamchk sees them. Indexes are numbered beginning with 1.

    If keys are not packed (PACK_KEYS=0), they have the same length, so when myisamchk sorts and moves records, it just overwrites record offsets in the index. If keys are packed (PACK_KEYS=1), myisamchk must unpack key blocks first, then re-create indexes and pack the key blocks again. (In this case, re-creating indexes is faster than updating offsets for each index.)

4.6.3.5. myisamchk Memory Usage

Memory allocation is important when you run myisamchk. myisamchk uses no more memory than its memory-related variables are set to. If you are going to use myisamchk on very large tables, you should first decide how much memory you want it to use. The default is to use only about 3MB to perform repairs. By using larger values, you can get myisamchk to operate faster. For example, if you have more than 32MB RAM, you could use options such as these (in addition to any other options you might specify):

shell> myisamchk --sort_buffer_size=16M --key_buffer_size=16M \
           --read_buffer_size=1M --write_buffer_size=1M ...

Using --sort_buffer_size=16M should probably be enough for most cases.

Be aware that myisamchk uses temporary files in TMPDIR. If TMPDIR points to a memory file system, you may easily get out of memory errors. If this happens, run myisamchk with the --tmpdir=path option to specify some directory located on a file system that has more space.

When repairing, myisamchk also needs a lot of disk space:

  • Double the size of the data file (the original file and a copy). This space is not needed if you do a repair with --quick; in this case, only the index file is re-created. This space must be available on the same file system as the original data file, as the copy is created in the same directory as the original.

  • Space for the new index file that replaces the old one. The old index file is truncated at the start of the repair operation, so you usually ignore this space. This space must be available on the same file system as the original data file.

  • When using --recover or --sort-recover (but not when using --safe-recover), you need space for a sort buffer. The following formula yields the amount of space required:

    (largest_key + row_pointer_length) × number_of_rows × 2
    

    You can check the length of the keys and the row_pointer_length with myisamchk -dv tbl_name. This space is allocated in the temporary directory (specified by TMPDIR or --tmpdir=path).

If you have a problem with disk space during repair, you can try --safe-recover instead of --recover.

4.6.4. myisamlog — Display MyISAM Log File Contents

myisamlog processes the contents of a MyISAM log file.

Invoke myisamlog like this:

shell> myisamlog [options] [log_file [tbl_name] ...]
shell> isamlog [options] [log_file [tbl_name] ...]

The default operation is update (-u). If a recovery is done (-r), all writes and possibly updates and deletes are done and errors are only counted. The default log file name is myisam.log for myisamlog and isam.log for isamlog if no log_file argument is given. If tables are named on the command line, only those tables are updated.

myisamlog supports the following options:

  • -?, -I

    Display a help message and exit.

  • -c N

    Execute only N commands.

  • -f N

    Specify the maximum number of open files.

  • -i

    Display extra information before exiting.

  • -o offset

    Specify the starting offset.

  • -p N

    Remove N components from path.

  • -r

    Perform a recovery operation.

  • -R record_pos_file record_pos

    Specify record position file and record position.

  • -u

    Perform an update operation.

  • -v

    Verbose mode. Print more output about what the program does. This option can be given multiple times to produce more and more output.

  • -w write_file

    Specify the write file.

  • -V

    Display version information.

4.6.5. myisampack — Generate Compressed, Read-Only MyISAM Tables

The myisampack utility compresses MyISAM tables. myisampack works by compressing each column in the table separately. Usually, myisampack packs the data file 40%–70%.

When the table is used later, the server reads into memory the information needed to decompress columns. This results in much better performance when accessing individual rows, because you only have to uncompress exactly one row.

MySQL uses mmap() when possible to perform memory mapping on compressed tables. If mmap() does not work, MySQL falls back to normal read/write file operations.

Please note the following:

  • If the mysqld server was invoked with external locking disabled, it is not a good idea to invoke myisampack if the table might be updated by the server during the packing process. It is safest to compress tables with the server stopped.

  • After packing a table, it becomes read only. This is generally intended (such as when accessing packed tables on a CD). Allowing writes to a packed table is on our TODO list, but with low priority.

Invoke myisampack like this:

shell> myisampack [options] file_name ...

Each file name argument should be the name of an index (.MYI) file. If you are not in the database directory, you should specify the path name to the file. It is permissible to omit the .MYI extension.

After you compress a table with myisampack, you should use myisamchk -rq to rebuild its indexes. Section 4.6.3, “myisamchk — MyISAM Table-Maintenance Utility”.

myisampack supports the options in the following list. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

  • --help, -?

    Display a help message and exit.

  • --backup, -b

    Make a backup of each table's data file using the name tbl_name.OLD.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o'.

  • --force, -f

    Produce a packed table even if it becomes larger than the original or if the intermediate file from an earlier invocation of myisampack exists. (myisampack creates an intermediate file named tbl_name.TMD in the database directory while it compresses the table. If you kill myisampack, the .TMD file might not be deleted.) Normally, myisampack exits with an error if it finds that tbl_name.TMD exists. With --force, myisampack packs the table anyway.

  • --join=big_tbl_name, -j big_tbl_name

    Join all tables named on the command line into a single packed table big_tbl_name. All tables that are to be combined must have identical structure (same column names and types, same indexes, and so forth).

    big_tbl_name must not exist prior to the join operation. All source tables named on the command line to be merged into big_tbl_name must exist. The source tables are read for the join operation but not modified. The join operation does not create a .frm file for big_tbl_name, so after the join operation finishes, copy the .frm file from one of the source tables and name it big_tbl_name.frm.

  • --silent, -s

    Silent mode. Write output only when errors occur.

  • --test, -t

    Do not actually pack the table, just test packing it.

  • --tmpdir=path, -T path

    Use the named directory as the location where myisampack creates temporary files.

  • --verbose, -v

    Verbose mode. Write information about the progress of the packing operation and its result.

  • --version, -V

    Display version information and exit.

  • --wait, -w

    Wait and retry if the table is in use. If the mysqld server was invoked with external locking disabled, it is not a good idea to invoke myisampack if the table might be updated by the server during the packing process.

The following sequence of commands illustrates a typical table compression session:

shell> ls -l station.*
-rw-rw-r--   1 monty    my         994128 Apr 17 19:00 station.MYD
-rw-rw-r--   1 monty    my          53248 Apr 17 19:00 station.MYI
-rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

shell> myisamchk -dvv station

MyISAM file:     station
Isam-version:  2
Creation time: 1996-03-13 10:08:58
Recover time:  1997-02-02  3:06:43
Data records:              1192  Deleted blocks:              0
Datafile parts:            1192  Deleted data:                0
Datafile pointer (bytes):     2  Keyfile pointer (bytes):     2
Max datafile length:   54657023  Max keyfile length:   33554431
Recordlength:               834
Record format: Fixed length

table description:
Key Start Len Index   Type                 Root  Blocksize    Rec/key
1   2     4   unique  unsigned long        1024       1024          1
2   32    30  multip. text                10240       1024          1

Field Start Length Type
1     1     1
2     2     4
3     6     4
4     10    1
5     11    20
6     31    1
7     32    30
8     62    35
9     97    35
10    132   35
11    167   4
12    171   16
13    187   35
14    222   4
15    226   16
16    242   20
17    262   20
18    282   20
19    302   30
20    332   4
21    336   4
22    340   1
23    341   8
24    349   8
25    357   8
26    365   2
27    367   2
28    369   4
29    373   4
30    377   1
31    378   2
32    380   8
33    388   4
34    392   4
35    396   4
36    400   4
37    404   1
38    405   4
39    409   4
40    413   4
41    417   4
42    421   4
43    425   4
44    429   20
45    449   30
46    479   1
47    480   1
48    481   79
49    560   79
50    639   79
51    718   79
52    797   8
53    805   1
54    806   1
55    807   20
56    827   4
57    831   4

shell> myisampack station.MYI
Compressing station.MYI: (1192 records)
- Calculating statistics

normal:     20  empty-space:   16  empty-zero:     12  empty-fill:  11
pre-space:   0  end-space:     12  table-lookups:   5  zero:         7
Original trees:  57  After join: 17
- Compressing file
87.14%
Remember to run myisamchk -rq on compressed tables

shell> ls -l station.*
-rw-rw-r--   1 monty    my         127874 Apr 17 19:00 station.MYD
-rw-rw-r--   1 monty    my          55296 Apr 17 19:04 station.MYI
-rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

shell> myisamchk -dvv station

MyISAM file:     station
Isam-version:  2
Creation time: 1996-03-13 10:08:58
Recover time:  1997-04-17 19:04:26
Data records:               1192  Deleted blocks:              0
Datafile parts:             1192  Deleted data:                0
Datafile pointer (bytes):      3  Keyfile pointer (bytes):     1
Max datafile length:    16777215  Max keyfile length:     131071
Recordlength:                834
Record format: Compressed

table description:
Key Start Len Index   Type                 Root  Blocksize    Rec/key
1   2     4   unique  unsigned long       10240       1024          1
2   32    30  multip. text                54272       1024          1

Field Start Length Type                         Huff tree  Bits
1     1     1      constant                             1     0
2     2     4      zerofill(1)                          2     9
3     6     4      no zeros, zerofill(1)                2     9
4     10    1                                           3     9
5     11    20     table-lookup                         4     0
6     31    1                                           3     9
7     32    30     no endspace, not_always              5     9
8     62    35     no endspace, not_always, no empty    6     9
9     97    35     no empty                             7     9
10    132   35     no endspace, not_always, no empty    6     9
11    167   4      zerofill(1)                          2     9
12    171   16     no endspace, not_always, no empty    5     9
13    187   35     no endspace, not_always, no empty    6     9
14    222   4      zerofill(1)                          2     9
15    226   16     no endspace, not_always, no empty    5     9
16    242   20     no endspace, not_always              8     9
17    262   20     no endspace, no empty                8     9
18    282   20     no endspace, no empty                5     9
19    302   30     no endspace, no empty                6     9
20    332   4      always zero                          2     9
21    336   4      always zero                          2     9
22    340   1                                           3     9
23    341   8      table-lookup                         9     0
24    349   8      table-lookup                        10     0
25    357   8      always zero                          2     9
26    365   2                                           2     9
27    367   2      no zeros, zerofill(1)                2     9
28    369   4      no zeros, zerofill(1)                2     9
29    373   4      table-lookup                        11     0
30    377   1                                           3     9
31    378   2      no zeros, zerofill(1)                2     9
32    380   8      no zeros                             2     9
33    388   4      always zero                          2     9
34    392   4      table-lookup                        12     0
35    396   4      no zeros, zerofill(1)               13     9
36    400   4      no zeros, zerofill(1)                2     9
37    404   1                                           2     9
38    405   4      no zeros                             2     9
39    409   4      always zero                          2     9
40    413   4      no zeros                             2     9
41    417   4      always zero                          2     9
42    421   4      no zeros                             2     9
43    425   4      always zero                          2     9
44    429   20     no empty                             3     9
45    449   30     no empty                             3     9
46    479   1                                          14     4
47    480   1                                          14     4
48    481   79     no endspace, no empty               15     9
49    560   79     no empty                             2     9
50    639   79     no empty                             2     9
51    718   79     no endspace                         16     9
52    797   8      no empty                             2     9
53    805   1                                          17     1
54    806   1                                           3     9
55    807   20     no empty                             3     9
56    827   4      no zeros, zerofill(2)                2     9
57    831   4      no zeros, zerofill(1)                2     9

myisampack displays the following kinds of information:

  • normal

    The number of columns for which no extra packing is used.

  • empty-space

    The number of columns containing values that are only spaces. These occupy one bit.

  • empty-zero

    The number of columns containing values that are only binary zeros. These occupy one bit.

  • empty-fill

    The number of integer columns that do not occupy the full byte range of their type. These are changed to a smaller type. For example, a BIGINT column (eight bytes) can be stored as a TINYINT column (one byte) if all its values are in the range from -128 to 127.

  • pre-space

    The number of decimal columns that are stored with leading spaces. In this case, each value contains a count for the number of leading spaces.

  • end-space

    The number of columns that have a lot of trailing spaces. In this case, each value contains a count for the number of trailing spaces.

  • table-lookup

    The column had only a small number of different values, which were converted to an ENUM before Huffman compression.

  • zero

    The number of columns for which all values are zero.

  • Original trees

    The initial number of Huffman trees.

  • After join

    The number of distinct Huffman trees left after joining trees to save some header space.

After a table has been compressed, myisamchk -dvv prints additional information about each column:

  • Type

    The data type. The value may contain any of the following descriptors:

    • constant

      All rows have the same value.

    • no endspace

      Do not store endspace.

    • no endspace, not_always

      Do not store endspace and do not do endspace compression for all values.

    • no endspace, no empty

      Do not store endspace. Do not store empty values.

    • table-lookup

      The column was converted to an ENUM.

    • zerofill(N)

      The most significant N bytes in the value are always 0 and are not stored.

    • no zeros

      Do not store zeros.

    • always zero

      Zero values are stored using one bit.

  • Huff tree

    The number of the Huffman tree associated with the column.

  • Bits

    The number of bits used in the Huffman tree.

After you run myisampack, you must run myisamchk to re-create any indexes. At this time, you can also sort the index blocks and create statistics needed for the MySQL optimizer to work more efficiently:

shell> myisamchk -rq --sort-index --analyze tbl_name.MYI

After you have installed the packed table into the MySQL database directory, you should execute mysqladmin flush-tables to force mysqld to start using the new table.

To unpack a packed table, use the --unpack option to myisamchk.

4.6.6. mysqlaccess — Client for Checking Access Privileges

mysqlaccess is a diagnostic tool that Yves Carlier has provided for the MySQL distribution. It checks the access privileges for a host name, user name, and database combination. Note that mysqlaccess checks access using only the user, db, and host tables. It does not check table, column, or routine privileges specified in the tables_priv, columns_priv, or procs_priv tables.

Invoke mysqlaccess like this:

shell> mysqlaccess [host_name [user_name [db_name]]] [options]

mysqlaccess supports the following options:

Table 4.10. mysqlaccess Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--briefbriefGenerate reports in single-line tabular format   
--commitcommitCopy the new access privileges from the temporary tables to the original grant tables   
--copycopyReload the temporary grant tables from original ones   
--db=db_namedbSpecify the database name   
--debug=#debugSpecify the debug level   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--howtohowtoDisplay some examples that show how to use mysqlaccess   
--old_serverold_serverAssume that the server is an old MySQL server (prior to MySQL 3.21)   
--password[=password]passwordThe password to use when connecting to the server   
--planplanDisplay suggestions and ideas for future releases   
--previewpreviewShow the privilege differences after making changes to the temporary grant tables   
--relnotesrelnotesDisplay the release notes   
--rhost=host_namerhostConnect to the MySQL server on the given host   
--rollbackrollbackUndo the most recent changes to the temporary grant tables.   
--spassword[=password]spasswordThe password to use when connecting to the server as the superuser   
--superuser=user_namesuperuserSpecify the user name for connecting as the superuser   
--tabletableGenerate reports in table format   
--user=user_name,userThe MySQL user name to use when connecting   
--version Display version information and exit   
  • --help, -?

    Display a help message and exit.

  • --brief, -b

    Generate reports in single-line tabular format.

  • --commit

    Copy the new access privileges from the temporary tables to the original grant tables. The grant tables must be flushed for the new privileges to take effect. (For example, execute a mysqladmin reload command.)

  • --copy

    Reload the temporary grant tables from original ones.

  • --db=db_name, -d db_name

    Specify the database name.

  • --debug=N

    Specify the debug level. N can be an integer from 0 to 3.

  • --host=host_name, -h host_name

    The host name to use in the access privileges.

  • --howto

    Display some examples that show how to use mysqlaccess.

  • --old_server

    Assume that the server is an old MySQL server (before MySQL 3.21) that does not yet know how to handle full WHERE clauses.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --plan

    Display suggestions and ideas for future releases.

  • --preview

    Show the privilege differences after making changes to the temporary grant tables.

  • --relnotes

    Display the release notes.

  • --rhost=host_name, -H host_name

    Connect to the MySQL server on the given host.

  • --rollback

    Undo the most recent changes to the temporary grant tables.

  • --spassword[=password], -P[password]

    The password to use when connecting to the server as the superuser. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --superuser=user_name, -U user_name

    Specify the user name for connecting as the superuser.

  • --table, -t

    Generate reports in table format.

  • --user=user_name, -u user_name

    The user name to use in the access privileges.

  • --version, -v

    Display version information and exit.

If your MySQL distribution is installed in some nonstandard location, you must change the location where mysqlaccess expects to find the mysql client. Edit the mysqlaccess script at approximately line 18. Search for a line that looks like this:

$MYSQL     = '/usr/local/bin/mysql';    # path to mysql executable

Change the path to reflect the location where mysql actually is stored on your system. If you do not do this, a Broken pipe error will occur when you run mysqlaccess.

4.6.7. mysqlbackup — Display Backup Information

mysqlbackup displays information from backup images created by the BACKUP DATABASE statement. This program was added in MySQL 6.0.11.

mysqlbackup has these capabilities:

  • List the objects contained in the backup image or information about the objects

  • Display the metadata (SQL statements to create objects in the backup image)

  • Search the backup image for a particular object

Invoke mysqlbackup like this:

shell> mysqlbackup [options] backup_image_file

With no options, mysqlbackup displays a short summary about the backup image:

shell> mysqlbackup /tmp/test.bak
Image path:          '/tmp/test.bak'
Image size:          12305 bytes
Image compression:   none
Image version:       1
Creation time:       2009-04-08 18:08:43 UTC
Server version:      6.0.11 (6.0.11-alpha)
Server byte order:   little-endian

mysqlbackup supports the following options. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

Table 4.11. mysqlbackup Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--allallDisplay everything except snapshots and data-chunks6.0.11  
--catalog-detailscatalog-detailsDisplay details of the database objects catalog6.0.11  
--catalog-summarycatalog-summaryDisplay summary of the database objects catalog6.0.11  
--data-chunksdata-chunksDisplay length of each data chunk contained in the backup image6.0.11  
--data-totalsdata-totalsDisplay length of data contained in the backup image for each object6.0.11  
--debug[=debug_options]debugWrite a debugging log6.0.11  
--exactexactDisplay exact number of bytes instead of KB, MB, GB units6.0.11  
--help Display help message and exit6.0.11  
--image-orderimage-orderDisplay catalog items and metadata in the order of the backup image6.0.11  
--metadata-extrametadata-extraDisplay extra metadata for the database objects6.0.11  
--metadata-statementsmetadata-statementsDisplay SQL statements that create the database objects6.0.11  
--open_files_limit=#open_files_limitHow many file descriptors to reserve6.0.11  
--search=namesearchSearch for object in the backup image6.0.11  
--snapshotssnapshotsDisplay information about snapshots contained in the backup image6.0.11  
--summarysummaryDisplay summary information from end of the backup image6.0.11  
--verbose Verbose mode6.0.11  
--version Display version information and exit6.0.11  
  • --help, -?

    Display a help message and exit.

  • --all

    Display everything except snapshots and data-chunks.

  • --catalog-details

    Display the details of the database objects catalog.

  • --catalog-summary

    Display summary of the database objects catalog.

  • --data-chunks

    Display the length of each data chunk contained in the backup image.

  • --data-totals

    Display the data length for each object contained in the backup image.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysqlbackup.trace'.

  • --exact

    Display lengths using the exact number of bytes instead of multiplier units such as KB, MB, and GB.

  • --image-order

    Display catalog items and metadata in the order of the backup image.

  • --metadata-extra

    Display extra metadata for the database objects.

  • --metadata-statements

    Display SQL statements that create the database objects in the backup image.

  • --open_files_limit=count

    Specify how many file descriptors to reserve.

  • --search=name

    Search for the given object in the backup image. The name can be object to find a global object or database.object to find a per-database object. Quoting of database and/or object with ", ', or ` is allowed. The wildcard characters '%' and '_' are available and have the same effect as for the LIKE operator. Use this option with the --metadata-* options to see metadata.

  • --snapshots

    Display information about snapshots contained in the backup image.

  • --summary

    Display a summary information from end of the backup image.

  • --verbose, -v

    Verbose mode. Include more information about the backup image in program output.

  • --version, -V

    Display version information and exit.

4.6.8. mysqlbinlog — Utility for Processing Binary Log Files

The server's binary log consists of files containing “events” that describe modifications to database contents. The server writes these files in binary format. To display their contents in text format, use the mysqlbinlog utility. You can also use mysqlbinlog to display the contents of relay log files written by a slave server in a replication setup because relay logs have the same format as binary logs. The binary log and relay log are discussed further in Section 5.2.4, “The Binary Log”, and Section 16.4.2, “Replication Relay and Status Files”.

Invoke mysqlbinlog like this:

shell> mysqlbinlog [options] log_file ...

For example, to display the contents of the binary log file named binlog.000003, use this command:

shell> mysqlbinlog binlog.0000003

The output includes events contained in binlog.000003. Event information includes the statement, the ID of the server on which it was executed, the timestamp when the statement was executed, how much time it took, and so forth.

The output from mysqlbinlog can be re-executed (for example, by using it as input to mysql) to reapply the statements in the log. This is useful for recovery operations after a server crash. For other usage examples, see the discussion later in this section.

Normally, you use mysqlbinlog to read binary log files directly and apply them to the local MySQL server. It is also possible to read binary logs from a remote server by using the --read-from-remote-server option. When you read remote binary logs, the connection parameter options can be given to indicate how to connect to the server. These options are --host, --password, --port, --protocol, --socket, and --user; they are ignored except when you also use the --read-from-remote-server option.

mysqlbinlog supports the following options. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.

Table 4.12. mysqlbinlog Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--base64-output[=value]base64-outputPrint binary log entries using base-64 encoding   
--character-sets-dir=pathcharacter-sets-dirThe directory where character sets are installed   
--database=db_namedatabaseList entries for just this database   
--debug[=debug_options]debugWrite a debugging log   
--debug-checkdebug-checkPrint debugging information when the program exits   
--debug-infodebug-infoPrint debugging information, memory and CPU statistics when the program exits   
--disable-log-bindisable-log-binDisable binary logging   
--force-readforce-readIf mysqlbinlog reads a binary log event that it does not recognize, it prints a warning   
--help Display help message and exit   
--hexdumphexdumpDisplay a hex dump of the log in comments   
--host=host_namehostConnect to the MySQL server on the given host   
--local-load=pathlocal-loadPrepare local temporary files for LOAD DATA INFILE in the specified directory   
--offset=#offsetSkip the first N entries in the log   
--password[=password]passwordThe password to use when connecting to the server   
--port=port_numportThe TCP/IP port number to use for the connection   
--protocol=typeprotocolThe connection protocol to use   
--read-from-remote-serverread-from-remote-serverRead the binary log from a MySQL server rather than reading a local log file   
--result-file=nameresult-fileDirect output to the given file   
--server-id=idserver-idExtract only those events created by the server having the given server ID   
--set-charset=charset_nameset-charsetAdd a SET NAMES charset_name statement to the output   
--short-formshort-formDisplay only the statements contained in the log   
--socket=pathsocketFor connections to localhost   
--start-datetime=datetimestart-datetimeStart reading the binary log at the first event having a timestamp equal to or later than the datetime argument   
--start-position=#start-positionStart reading the binary log at the first event having a position equal to or greater than the argument   
--stop-datetime=datetimestop-datetimeStop reading the binary log at the first event having a timestamp equal to or greater than the datetime argument   
--stop-position=#stop-positionStop reading the binary log at the first event having a position equal to or greater than the argument   
--to-last-logto-last-logDo not stop at the end of the requested binary log from a MySQL server, but rather continue printing until the end of the last binary log   
--user=user_name,userThe MySQL user name to use when connecting to the server   
--verbose Reconstruct row events as SQL statements6.0.7  
--version Display version information and exit   
--write-binlogwrite-binlogLog ANALYZE, OPTIMIZE, REPAIR statements to binary log. --skip-write-binlog adds NO_WRITE_TO_BINLOG to these statements.   
  • --help, -?

    Display a help message and exit.

  • --base64-output[=value]

    This option determines when events should be displayed encoded as base-64 strings using BINLOG statements. The option has these allowable values (not case sensitive):

    • AUTO ("automatic") or UNSPEC ("unspecified") displays BINLOG statements automatically when necessary (that is, for format description events and row events). This is the default if no --base64-output option is given.

      Note

      Automatic BINLOG display is the only safe behavior if you intend to use the output of mysqlbinlog to re-execute binary log file contents. The other option values are intended only for debugging or testing purposes because they may produce output that does not include all events in executable form.

    • ALWAYS displays BINLOG statements whenever possible. This is the implied value if the option is given as --base64-output without a value.

    • NEVER causes BINLOG statements not to be displayed. mysqlbinlog exits with an error if a row event is found that must be displayed using BINLOG.

    • DECODE-ROWS specifies to mysqlbinlog that you intend for row events to be decoded and displayed as commented SQL statements by also specifying the --verbose option. Like NEVER, DECODE-ROWS suppresses display of BINLOG statements, but unlike NEVER, it does not exit with an error if a row event is found.

    Before MySQL 6.0.4, the --base64-output option was boolean, to be given as --base64-output or --skip-base64-output (with the sense of AUTO or NEVER). The option values described in the preceding list may be used as of MySQL 6.0.4, with the exception of UNSPEC and DECODE-ROWS, which are available as of MySQL 6.0.7.

    For examples that show the effect of --base64-output and --verbose on row event output, see Section 4.6.8.2, “mysqlbinlog Row Event Display”.

  • --character-sets-dir=path

    The directory where character sets are installed. See Section 9.2, “The Character Set Used for Data and Sorting”.

  • --database=db_name, -d db_name

    List entries for just this database (local log only). You can only specify one database with this option - if you specify multiple --database options, only the last one is used. This option forces mysqlbinlog to output entries from the binary log where the default database (that is, the one selected by USE) is db_name. Note that this does not replicate cross-database statements such as UPDATE some_db.some_table SET foo='bar' while having selected a different database or no database.

  • --debug[=debug_options], -# [debug_options]

    Write a debugging log. A typical debug_options string is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysqlbinlog.trace'.

  • --debug-check

    Print some debugging information when the program exits.

  • --debug-info

    Print debugging information and memory and CPU usage statistics when the program exits.

  • --disable-log-bin, -D

    Disable binary logging. This is useful for avoiding an endless loop if you use the --to-last-log option and are sending the output to the same MySQL server. This option also is useful when restoring after a crash to avoid duplication of the statements you have logged.

    This option requires that you have the SUPER privilege. It causes mysqlbinlog to include a SET sql_log_bin = 0 statement in its output to disable binary logging of the remaining output. The SET statement is ineffective unless you have the SUPER privilege.

  • --force-read, -f

    With this option, if mysqlbinlog reads a binary log event that it does not recognize, it prints a warning, ignores the event, and continues. Without this option, mysqlbinlog stops if it reads such an event.

  • --hexdump, -H

    Display a hex dump of the log in comments, as described in Section 4.6.8.1, “mysqlbinlog Hex Dump Format”. This output can be helpful for replication debugging.

  • --host=host_name, -h host_name

    Get the binary log from the MySQL server on the given host.

  • --local-load=path, -l path

    Prepare local temporary files for LOAD DATA INFILE in the specified directory.

  • --offset=N, -o N

    Skip the first N entries in the log.

  • --password[=password], -p[password]

    The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --port=port_num, -P port_num

    The TCP/IP port number to use for connecting to a remote server.

  • --position=N, -j N

    Deprecated. Use --start-position instead.

  • --protocol={TCP|SOCKET|PIPE|MEMORY}

    The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the allowable values, see Section 4.2.2, “Connecting to the MySQL Server”.

  • --read-from-remote-server, -R

    Read the binary log from a MySQL server rather than reading a local log file. Any connection parameter options are ignored unless this option is given as well. These options are --host, --password, --port, --protocol, --socket, and --user.

    This option requires that the remote server be running. It works only for binary log files on the remote server, not relay log files.

  • --result-file=name, -r name

    Direct output to the given file.

  • --server-id=id

    Extract only those events created by the server having the given server ID.

  • --set-charset=charset_name

    Add a SET NAMES charset_name statement to the output to specify the character set to be used for processing log files.

  • --short-form, -s

    Display only the statements contained in the log, without any extra information.

  • --socket=path, -S path

    For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

  • --start-datetime=datetime

    Start reading the binary log at the first event having a timestamp equal to or later than the datetime argument. The datetime value is relative to the local time zone on the machine where you run mysqlbinlog. The value should be in a format accepted for the DATETIME or TIMESTAMP data types. For example:

    shell> mysqlbinlog --start-datetime="2005-12-25 11:25:56" binlog.000003
    

    This option is useful for point-in-time recovery. See Section 6.2, “Example Backup and Recovery Strategy”.

  • --start-position=N

    Start reading the binary log at the first event having a position equal to or greater than N. This option applies to the first log file named on the command line.

  • --stop-datetime=datetime

    Stop reading the binary log at the first event having a timestamp equal to or later than the datetime argument. This option is useful for point-in-time recovery. See the description of the --start-datetime option for information about the datetime value.

  • --stop-position=N

    Stop reading the binary log at the first event having a position equal to or greater than N. This option applies to the last log file named on the command line.

  • --to-last-log, -t

    Do not stop at the end of the requested binary log from a MySQL server, but rather continue printing until the end of the last binary log. If you send the output to the same MySQL server, this may lead to an endless loop. This option requires --read-from-remote-server.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to a remote server.

  • --verbose, -v

    Reconstruct row events and display them as commented SQL statements. If given twice, the output includes comments to indicate column data types and some metadata. This option was added in MySQL 6.0.7.

    For examples that show the effect of --base64-output and --verbose on row event output, see Section 4.6.8.2, “mysqlbinlog Row Event Display”.

  • --version, -V

    Display version information and exit.

  • --write-binlog

    This option is enabled by default, so that ANALYZE TABLE, OPTIMIZE TABLE, and REPAIR TABLE statements generated by mysqlcheck are written to the binary log. Use --skip-write-binlog to cause NO_WRITE_TO_BINLOG to be added to the statements so that they are not logged. Use the --skip-write-binlog when these statements should not be sent to replication slaves or run when using the binary logs for recovery from backup.

You can also set the following variable by using --var_name=value syntax:

  • open_files_limit

    Specify the number of open file descriptors to reserve.

You can pipe the output of mysqlbinlog into the mysql client to execute the statements contained in the binary log. This is used to recover from a crash when you have an old backup (see Section 6.1, “Database Backups”). For example:

shell> mysqlbinlog binlog.000001 | mysql

Or:

shell> mysqlbinlog binlog.[0-9]* | mysql

You can also redirect the output of mysqlbinlog to a text file instead, if you need to modify the statement log first (for example, to remove statements that you do not want to execute for some reason). After editing the file, execute the statements that it contains by using it as input to the mysql program.

mysqlbinlog has the --start-position option, which prints only those statements with an offset in the binary log greater than or equal to a given position (the given position must match the start of one event). It also has options to stop and start when it sees an event with a given date and time. This enables you to perform point-in-time recovery using the --stop-datetime option (to be able to say, for example, “roll forward my databases to how they were today at 10:30 a.m.”).

If you have more than one binary log to execute on the MySQL server, the safe method is to process them all using a single connection to the server. Here is an example that demonstrates what may be unsafe:

shell> mysqlbinlog binlog.000001 | mysql # DANGER!!
shell> mysqlbinlog binlog.000002 | mysql # DANGER!!

Processing binary logs this way using different connections to the server causes problems if the first log file contains a CREATE TEMPORARY TABLE statement and the second log contains a statement that uses the temporary table. When the first mysql process terminates, the server drops the temporary table. When the second mysql process attempts to use the table, the server reports “unknown table.

To avoid problems like this, use a single connection to execute the contents of all binary logs that you want to process. Here is one way to do so:

shell> mysqlbinlog binlog.000001 binlog.000002 | mysql

Another approach is to write all the logs to a single file and then process the file:

shell> mysqlbinlog binlog.000001 >  /tmp/statements.sql
shell> mysqlbinlog binlog.000002 >> /tmp/statements.sql
shell> mysql -e "source /tmp/statements.sql"

mysqlbinlog can produce output that reproduces a LOAD DATA INFILE operation without the original data file. mysqlbinlog copies the data to a temporary file and writes a LOAD DATA LOCAL INFILE statement that refers to the file. The default location of the directory where these files are written is system-specific. To specify a directory explicitly, use the --local-load option.

Because mysqlbinlog converts LOAD DATA INFILE statements to LOAD DATA LOCAL INFILE statements (that is, it adds LOCAL), both the client and the server that you use to process the statements must be configured to allow LOCAL capability. See Section 5.3.4, “Security Issues with LOAD DATA LOCAL.

MySQL Enterprise For expert advice on the security implications of enabling LOCAL, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

Warning

The temporary files created for LOAD DATA LOCAL statements are not automatically deleted because they are needed until you actually execute those statements. You should delete the temporary files yourself after you no longer need the statement log. The files can be found in the temporary file directory and have names like original_file_name-#-#.

4.6.8.1. mysqlbinlog Hex Dump Format

The --hexdump option produces a hex dump of the log contents:

shell> mysqlbinlog --hexdump master-bin.000001

The hex output consists of comment lines beginning with #, so the output might look like this for the preceding command:

/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
# at 4
#051024 17:24:13 server id 1  end_log_pos 98
# Position  Timestamp   Type   Master ID        Size      Master Pos    Flags
# 00000004 9d fc 5c 43   0f   01 00 00 00   5e 00 00 00   62 00 00 00   00 00
# 00000017 04 00 35 2e 30 2e 31 35  2d 64 65 62 75 67 2d 6c |..5.0.15.debug.l|
# 00000027 6f 67 00 00 00 00 00 00  00 00 00 00 00 00 00 00 |og..............|
# 00000037 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 |................|
# 00000047 00 00 00 00 9d fc 5c 43  13 38 0d 00 08 00 12 00 |.......C.8......|
# 00000057 04 04 04 04 12 00 00 4b  00 04 1a                |.......K...|
#       Start: binlog v 4, server v 5.0.15-debug-log created 051024 17:24:13
#       at startup
ROLLBACK;

Hex dump output currently contains the following elements. This format is subject to change.

  • Position: The byte position within the log file.

  • Timestamp: The event timestamp. In the example shown, '9d fc 5c 43' is the representation of '051024 17:24:13' in hexadecimal.

  • Type: The event type code. In the example shown, '0f' indicates a FORMAT_DESCRIPTION_EVENT. The following table lists the possible type codes.

    TypeNameMeaning
    00UNKNOWN_EVENTThis event should never be present in the log.
    01START_EVENT_V3This indicates the start of a log file written by MySQL 4 or earlier.
    02QUERY_EVENTThe most common type of events. These contain statements executed on the master.
    03STOP_EVENTIndicates that master has stopped.
    04ROTATE_EVENTWritten when the master switches to a new log file.
    05INTVAR_EVENTUsed for AUTO_INCREMENT values or when the LAST_INSERT_ID() function is used in the statement.
    06LOAD_EVENTUsed for LOAD DATA INFILE in MySQL 3.23.
    07SLAVE_EVENTReserved for future use.
    08CREATE_FILE_EVENTUsed for LOAD DATA INFILE statements. This indicates the start of execution of such a statement. A temporary file is created on the slave. Used in MySQL 4 only.
    09APPEND_BLOCK_EVENTContains data for use in a LOAD DATA INFILE statement. The data is stored in the temporary file on the slave.
    0aEXEC_LOAD_EVENTUsed for LOAD DATA INFILE statements. The contents of the temporary file is stored in the table on the slave. Used in MySQL 4 only.
    0bDELETE_FILE_EVENTRollback of a LOAD DATA INFILE statement. The temporary file should be deleted on the slave.
    0cNEW_LOAD_EVENTUsed for LOAD DATA INFILE in MySQL 4 and earlier.
    0dRAND_EVENTUsed to send information about random values if the RAND() function is used in the statement.
    0eUSER_VAR_EVENTUsed to replicate user variables.
    0fFORMAT_DESCRIPTION_EVENTThis indicates the start of a log file written by MySQL 5 or later.
    10XID_EVENTEvent indicating commit of an XA transaction.
    11BEGIN_LOAD_QUERY_EVENTUsed for LOAD DATA INFILE statements in MySQL 5 and later.
    12EXECUTE_LOAD_QUERY_EVENTUsed for LOAD DATA INFILE statements in MySQL 5 and later.
    13TABLE_MAP_EVENTInformation about a table definition. Used in MySQL 5.1.5 and later.
    14PRE_GA_WRITE_ROWS_EVENTRow data for a single table that should be created. Used in MySQL 5.1.5 to 5.1.17.
    15PRE_GA_UPDATE_ROWS_EVENTRow data for a single table that needs to be updated. Used in MySQL 5.1.5 to 5.1.17.
    16PRE_GA_DELETE_ROWS_EVENTRow data for a single table that should be deleted. Used in MySQL 5.1.5 to 5.1.17.
    17WRITE_ROWS_EVENTRow data for a single table that should be created. Used in MySQL 5.1.18 and later.
    18UPDATE_ROWS_EVENTRow data for a single table that needs to be updated. Used in MySQL 5.1.18 and later.
    19DELETE_ROWS_EVENTRow data for a single table that should be deleted. Used in MySQL 5.1.18 and later.
    1aINCIDENT_EVENTSomething out of the ordinary happened. Added in MySQL 5.1.18.
    1bHEARTBEAT_LOG_EVENTHeartbeat sent by master to slave. Added in MySQL 6.0.5.
  • Master ID: The server ID of the master that created the event.

  • Size: The size in bytes of the event.

  • Master Pos: The position of the next event in the original master log file.

  • Flags: 16 flags. Currently, the following flags are used. The others are reserved for future use.

    FlagNameMeaning
    01LOG_EVENT_BINLOG_IN_USE_FLog file correctly closed. (Used only in FORMAT_DESCRIPTION_EVENT.) If this flag is set (if the flags are, for example, '01 00') in a FORMAT_DESCRIPTION_EVENT, the log file has not been properly closed. Most probably this is because of a master crash (for example, due to power failure).
    02 Reserved for future use.
    04LOG_EVENT_THREAD_SPECIFIC_FSet if the event is dependent on the connection it was executed in (for example, '04 00'), for example, if the event uses temporary tables.
    08LOG_EVENT_SUPPRESS_USE_FSet in some circumstances when the event is not dependent on the default database.

4.6.8.2. mysqlbinlog Row Event Display

The following examples illustrate how mysqlbinlog displays row events that specify data modifications. These correspond to events with the WRITE_ROWS_EVENT, UPDATE_ROWS_EVENT, and DELETE_ROWS_EVENT type codes. The --base64-output=DECODE-ROWS and --verbose options may be used to affect row event output. These options are available as of MySQL 6.0.7.

Suppose that the server is using row-based binary logging and that you execute the following sequence of statements:

CREATE TABLE t
(
  id   INT NOT NULL,
  name VARCHAR(20) NOT NULL,
  date DATE NULL
) ENGINE = InnoDB;

START TRANSACTION;
INSERT INTO t VALUES(1, 'apple', NULL);
UPDATE t SET name = 'pear', date = '2009-01-01' WHERE id = 1;
DELETE FROM t WHERE id = 1;
COMMIT;

By default, mysqlbinlog displays row events encoded as base-64 strings using BINLOG statements. Omitting extraneous lines, the output for the row events produced by the preceding statement sequence looks like this:

shell> mysqlbinlog log_file
...
# at 218
#080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAANoAAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBcBAAAAKAAAAAIBAAAQABEAAAAAAAEAA//8AQAAAAVhcHBsZQ==
'/*!*/;
...
# at 302
#080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAAC4BAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBgBAAAANgAAAGQBAAAQABEAAAAAAAEAA////AEAAAAFYXBwbGX4AQAAAARwZWFyIbIP
'/*!*/;
...
# at 400
#080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAAJABAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBkBAAAAKgAAALoBAAAQABEAAAAAAAEAA//4AQAAAARwZWFyIbIP
'/*!*/;

To see the row events as comments in the form of “pseudo-SQL” statements, run mysqlbinlog with the --verbose or -v option. The output will contain lines beginning with ###:

shell> mysqlbinlog -v log_file
...
# at 218
#080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAANoAAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBcBAAAAKAAAAAIBAAAQABEAAAAAAAEAA//8AQAAAAVhcHBsZQ==
'/*!*/;
### INSERT INTO test.t
### SET
###   @1=1
###   @2='apple'
###   @3=NULL
...
# at 302
#080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAAC4BAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBgBAAAANgAAAGQBAAAQABEAAAAAAAEAA////AEAAAAFYXBwbGX4AQAAAARwZWFyIbIP
'/*!*/;
### UPDATE test.t
### WHERE
###   @1=1
###   @2='apple'
###   @3=NULL
### SET
###   @1=1
###   @2='pear'
###   @3='2009:01:01'
...
# at 400
#080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAAJABAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBkBAAAAKgAAALoBAAAQABEAAAAAAAEAA//4AQAAAARwZWFyIbIP
'/*!*/;
### DELETE FROM test.t
### WHERE
###   @1=1
###   @2='pear'
###   @3='2009:01:01'

Specify --verbose or -v twice to also display data types and some metadata for each column. The output will contain an additional comment following each column change:

shell> mysqlbinlog -vv log_file
...
# at 218
#080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAANoAAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBcBAAAAKAAAAAIBAAAQABEAAAAAAAEAA//8AQAAAAVhcHBsZQ==
'/*!*/;
### INSERT INTO test.t
### SET
###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
###   @2='apple' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
###   @3=NULL /* VARSTRING(20) meta=0 nullable=1 is_null=1 */
...
# at 302
#080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAAC4BAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBgBAAAANgAAAGQBAAAQABEAAAAAAAEAA////AEAAAAFYXBwbGX4AQAAAARwZWFyIbIP
'/*!*/;
### UPDATE test.t
### WHERE
###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
###   @2='apple' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
###   @3=NULL /* VARSTRING(20) meta=0 nullable=1 is_null=1 */
### SET
###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
###   @2='pear' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
###   @3='2009:01:01' /* DATE meta=0 nullable=1 is_null=0 */
...
# at 400
#080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F

BINLOG '
fAS3SBMBAAAALAAAAJABAAAAABEAAAAAAAAABHRlc3QAAXQAAwMPCgIUAAQ=
fAS3SBkBAAAAKgAAALoBAAAQABEAAAAAAAEAA//4AQAAAARwZWFyIbIP
'/*!*/;
### DELETE FROM test.t
### WHERE
###   @1=1 /* INT meta=0 nullable=0 is_null=0 */
###   @2='pear' /* VARSTRING(20) meta=20 nullable=0 is_null=0 */
###   @3='2009:01:01' /* DATE meta=0 nullable=1 is_null=0 */

You can tell mysqlbinlog to suppress the BINLOG statements for row events by using the --base64-output=DECODE-ROWS option. This is similar to --base64-output=NEVER but does not exit with an error if a row event is found. The combination of --base64-output=DECODE-ROWS and --verbose provides a convenient way to see row events only as SQL statements:

shell> mysqlbinlog -v --base64-output=DECODE-ROWS log_file
...
# at 218
#080828 15:03:08 server id 1  end_log_pos 258 	Write_rows: table id 17 flags: STMT_END_F
### INSERT INTO test.t
### SET
###   @1=1
###   @2='apple'
###   @3=NULL
...
# at 302
#080828 15:03:08 server id 1  end_log_pos 356 	Update_rows: table id 17 flags: STMT_END_F
### UPDATE test.t
### WHERE
###   @1=1
###   @2='apple'
###   @3=NULL
### SET
###   @1=1
###   @2='pear'
###   @3='2009:01:01'
...
# at 400
#080828 15:03:08 server id 1  end_log_pos 442 	Delete_rows: table id 17 flags: STMT_END_F
### DELETE FROM test.t
### WHERE
###   @1=1
###   @2='pear'
###   @3='2009:01:01'

Note

You should not suppress BINLOG statements if you intend to re-execute mysqlbinlog output.

The SQL statements produced by --verbose for row events are much more readable than the corresponding BINLOG statements. However, they do not correspond exactly to the original SQL statements that generated the events. The following limitations apply:

  • The original column names are lost and replaced by @N, where N is a column number.

  • Character set information is not available in the binary log, which affects string column display:

    • There is no distinction made between corresponding binary and nonbinary string types (BINARY and CHAR, VARBINARY and VARCHAR, BLOB and TEXT). The output uses a data type of STRING for fixed-length strings and VARSTRING for variable-length strings.

    • For multi-byte character sets, the maximum number of bytes per character is not present in the binary log, so the length for string types is displayed in bytes rather than in characters. For example, STRING(4) will be used as the data type for values from either of these column types:

      CHAR(4) CHARACTER SET latin1
      CHAR(2) CHARACTER SET ucs2
      
    • Due to the storage format for events of type UPDATE_ROWS_EVENT, UPDATE statements are displayed with the WHERE clause preceding the SET clause.

Proper interpretation of row events requires the information from the format description event at the beginning of the binary log. Because mysqlbinlog does not know in advance whether the rest of the log contains row events, by default it displays the format description event using a BINLOG statement in the initial part of the output.

If the binary log is known not to contain any events requiring a BINLOG statement (that is, no row events), the --base64-output=NEVER option can be used to prevent this header from being written.

4.6.9. mysqldumpslow — Summarize Slow Query Log Files

The MySQL slow query log contains information about queries that take a long time to execute (see Section 5.2.5, “The Slow Query Log”). mysqldumpslow parses MySQL slow query log files and prints a summary of their contents.

Normally, mysqldumpslow groups queries that are similar except for the particular values of number and string data values. It “abstracts” these values to N and 'S' when displaying summary output. The -a and -n options can be used to modify value abstracting behavior.

Invoke mysqldumpslow like this:

shell> mysqldumpslow [options] [log_file ...]

Table 4.13. mysqldumpslow Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
-a Do not abstract all numbers to N and strings to S   
-n num Abstract numbers with at least the specified digits   
--debugdebugWrite debugging information   
-g pattern Only consider statements that match the pattern   
--help Display help message and exit   
-h name Host name of the server in the log file name   
-i name Name of the server instance   
-l Do not subtract lock time from total time   
-r Reverse the sort order   
-s value How to sort output   
-t num Display only first num queries   
--verboseverboseVerbose mode   

mysqldumpslow supports the following options:

  • --help

    Display a help message and exit.

  • -a

    Do not abstract all numbers to N and strings to 'S'.

  • --debug, -d

    Run in debug mode.

  • -g pattern

    Consider only queries that match the (grep-style) pattern.

  • -h host_name

    Host name of MySQL server for *-slow.log file name. The value can contain a wildcare. The default is * (match all).

  • -i name

    Name of server instance (if using mysql.server startup script).

  • -l

    Do not subtract lock time from total time.

  • -n N

    Abstract numbers with at least N digits within names.

  • -r

    Reverse the sort order.

  • -s sort_type

    How to sort the output. The value of sort_type should be chosen from the following list:

    • t, at: Sort by query time or average query time

    • l, al: Sort by lock time or average lock time

    • s, as: Sort by rows sent or average rows sent

    • c: Sort by count

  • -t N

    Display only the first N queries in the output.

  • --verbose, -v

    Verbose mode. Print more information about what the program does.

Example of usage:

shell> mysqldumpslow

Reading mysql slow query log from /usr/local/mysql/data/mysqld51-apple-slow.log
Count: 1  Time=4.32s (4s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost
 insert into t2 select * from t1

Count: 3  Time=2.53s (7s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost
 insert into t2 select * from t1 limit N

Count: 3  Time=2.13s (6s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost
 insert into t1 select * from t1

4.6.10. mysqlhotcopy — A Database Backup Program

mysqlhotcopy is a Perl script that was originally written and contributed by Tim Bunce. It uses LOCK TABLES, FLUSH TABLES, and cp or scp to make a database backup quickly. It is the fastest way to make a backup of the database or single tables, but it can be run only on the same machine where the database directories are located. mysqlhotcopy works only for backing up MyISAM and ARCHIVE tables. It runs on Unix and NetWare.

shell> mysqlhotcopy db_name [/path/to/new_directory]
shell> mysqlhotcopy db_name_1 ... db_name_n /path/to/new_directory

Back up tables in the given database that match a regular expression:

shell> mysqlhotcopy db_name./regex/

The regular expression for the table name can be negated by prefixing it with a tilde (“~”):

shell> mysqlhotcopy db_name./~regex/

Table 4.14. mysqlhotcopy Option Reference

FormatConfig FileDescriptionIntroductionDeprecatedRemoved
--addtodestaddtodestDo not rename target directory (if it exists); merely add files to it   
--allowoldallowoldDo not abort if a target exists; rename it by adding an _old suffix   
--checkpoint=db_name.tbl_namecheckpointInsert checkpoint entries   
--chroot=pathchrootBase directory of the chroot jail in which mysqld operates   
--debugdebugWrite a debugging log   
--dryrundryrunReport actions without performing them   
--flushlogflushlogFlush logs after all tables are locked   
--help Display help message and exit   
--host=host_namehostConnect to the MySQL server on the given host   
--keepoldkeepoldDo not delete previous (renamed) target when done   
--noindicesnoindicesDo not include full index files in the backup   
--password[=password]passwordThe password to use when connecting to the server   
--port=port_numportThe TCP/IP port number to use for the connection   
--quietquietBe silent except for errors   
--regexpregexpCopy all databases with names that match the given regular expression   
--resetmasterresetmasterReset the binary log after locking all the tables   
--resetslaveresetslaveReset the master.info file after locking all the tables   
--socket=pathsocketFor connections to localhost   
--tmpdir=pathtmpdirThe temporary directory   
--user=user_name,userThe MySQL user name to use when connecting to the server   

mysqlhotcopy supports the following options:

  • --help, -?

    Display a help message and exit.

  • --addtodest

    Do not rename target directory (if it exists); merely add files to it.

  • --allowold

    Do not abort if a target exists; rename it by adding an _old suffix.

  • --checkpoint=db_name.tbl_name

    Insert checkpoint entries into the specified database db_name and table tbl_name.

  • --chroot=path

    Base directory of the chroot jail in which mysqld operates. The path value should match that of the --chroot option given to mysqld.

  • --debug

    Enable debug output.

  • --dryrun, -n

    Report actions without performing them.

  • --flushlog

    Flush logs after all tables are locked.

  • --host=host_name, -h host_name

    The host name of the local host to use for making a TCP/IP connection to the local server. By default, the connection is made to localhost using a Unix socket file.

  • --keepold

    Do not delete previous (renamed) target when done.

  • --method=command

    The method for copying files (cp or scp).

  • --noindices

    Do not include full index files in the backup. This makes the backup smaller and faster. The indexes for reloaded tables can be reconstructed later with myisamchk -rq.

  • --password=password, -ppassword

    The password to use when connecting to the server. Note that the password value is not optional for this option, unlike for other MySQL programs. You can use an option file to avoid giving the password on the command line.

    Specifying a password on the command line should be considered insecure. See Section 5.5.6.2, “End-User Guidelines for Password Security”.

  • --port=port_num, -P port_num

    The TCP/IP port number to use when connecting to the local server.

  • --quiet, -q

    Be silent except for errors.

  • --record_log_pos=db_name.tbl_name

    Record master and slave status in the specified database db_name and table tbl_name.

  • --regexp=expr

    Copy all databases with names that match the given regular expression.

  • --resetmaster

    Reset the binary log after locking all the tables.

  • --resetslave

    Reset the master.info file after locking all the tables.

  • --socket=path, -S path

    The Unix socket file to use for the connection.

  • --suffix=str

    The suffix for names of copied databases.

  • --tmpdir=path

    The temporary directory. The default is /tmp.

  • --user=user_name, -u user_name

    The MySQL user name to use when connecting to the server.

mysqlhotcopy reads the [client] and [mysqlhotcopy] option groups from option files.

To execute mysqlhotcopy, you must have access to the files for the tables that you are backing up, the SELECT privilege for those tables, the RELOAD privilege (to be able to execute FLUSH TABLES), and the LOCK TABLES privilege (to be able to lock the tables).

Use perldoc for additional mysqlhotcopy documentation, including information about the structure of the tables needed for the --checkpoint and --record_log_pos options:

shell> perldoc mysqlhotcopy

MySQL Enterprise MySQL Enterprise subscribers will find more information about mysqlhotcopy in the Knowledge Base article, How Does mysqlhotcopy Work?. Access to the MySQL Knowledge Base collection of articles is one of the advantages of subscribing to MySQL Enterprise. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

4.6.11. mysql_convert_table_format — Convert Tables to Use a Given Storage Engine

mysql_convert_table_format converts the tables in a database to use a particular storage engine (MyISAM by default). mysql_convert_table_format is written in Perl and requires that the DBI and DBD::mysql Perl modules be installed (see Section 2.14, “Perl Installation Notes”).

Invoke mysql_convert_table_format like this:

shell> mysql_convert_table_format [options]db_name

The db_name argument indicates the database containing the tables to be converted.

mysql_convert_table_format supports the options described in the following list.

4.6.12. mysql_find_rows — Extract SQL Statements from Files

mysql_find_rows reads files containing SQL statements and extracts statements that match a given regular expression or that contain USE db_name or SET statements. The utility was written for use with update log files (as used prior to MySQL 5.0) and as such expects statements to be terminated with semicolon (;) characters. It may be useful with other files that contain SQL statements as long as statements are terminated with semicolons.

Invoke mysql_find_rows like this:

shell> mysql_find_rows [options] [file_name ...]

Each file_name argument should be the name of file containing SQL statements. If no file names are given, mysql_find_rows reads the standard input.

Examples:

mysql_find_rows --regexp=problem_table --rows=20 < update.log
mysql_find_rows --regexp=problem_table  update-log.1 update-log.2

mysql_find_rows supports the following options:

4.6.13. mysql_fix_extensions — Normalize Table File Name Extensions

mysql_fix_extensions converts the extensions for MyISAM (or ISAM) table files to their canonical forms. It looks for files with extensions matching any lettercase variant of .frm, .myd, .myi, .isd, and .ism and renames them to have extensions of .frm, .MYD, .MYI, .ISD, and .ISM, respectively. This can be useful after transferring the files from a system with case-insensitive file names (such as Windows) to a system with case-sensitive file names.

Invoke mysql_fix_extensions like this, where data_dir is the path name to the MySQL data directory.

shell> mysql_fix_extensions data_dir

4.6.14. mysql_setpermission — Interactively Set Permissions in Grant Tables

mysql_setpermission is a Perl script that was originally written and contributed by Luuk de Boer. It interactively sets permissions in the MySQL grant tables. mysql_setpermission is written in Perl and requires that the DBI and DBD::mysql Perl modules be installed (see Section 2.14, “Perl Installation Notes”).

Invoke mysql_setpermission like this:

shell> mysql_setpermission [options]

options should be either --help to display the help message, or options that indicate how to connect to the MySQL server. The account used when you connect determines which permissions you have when attempting to modify existing permissions in the grant tables.

mysql_setpermissions also reads options from the [client] and [perl] groups in the .my.cnf file in your home directory, if the file exists.

mysql_setpermission supports the following options:

4.6.15. mysql_waitpid — Kill Process and Wait for Its Termination

mysql_waitpid signals a process to terminate and waits for the process to exit. It uses the kill() system call and Unix signals, so it runs on Unix and Unix-like systems.

Invoke mysql_waitpid like this:

shell> mysql_waitpid [options] pid wait_time

mysql_waitpid sends signal 0 to the process identified by pid and waits up to wait_time seconds for the process to terminate. pid and wait_time must be positive integers.

If process termination occurs within the wait time or the process does not exist, mysql_waitpid returns 0. Otherwise, it returns 1.

If the kill() system call cannot handle signal 0, mysql_waitpid() uses signal 1 instead.

mysql_waitpid supports the following options:

  • --help, -?, -I

    Display a help message and exit.

  • --verbose, -v

    Verbose mode. Display a warning if signal 0 could not be used and signal 1 is used instead.

  • --version, -V

    Display version information and exit.

4.6.16. mysql_zap — Kill Processes That Match a Pattern

mysql_zap kills processes that match a pattern. It uses the ps command and Unix signals, so it runs on Unix and Unix-like systems.

Invoke mysql_zap like this:

shell> mysql_zap [-signal] [-?Ift] pattern

A process matches if its output line from the ps command contains the pattern. By default, mysql_zap asks for confirmation for each process. Respond y to kill the process, or q to exit mysql_zap. For any other response, mysql_zap does not attempt to kill the process.

If the -signal option is given, it specifies the name or number of the signal to send to each process. Otherwise, mysql_zap tries first with TERM (signal 15) and then with KILL (signal 9).

mysql_zap supports the following additional options:

  • --help, -?, -I

    Display a help message and exit.

  • -f

    Force mode. mysql_zap attempts to kill each process without confirmation.

  • -t

    Test mode. Display information about each process but do not kill it.

4.7. MySQL Program Development Utilities

This section describes some utilities that you may find useful when developing MySQL programs.

In shell scripts, you can use the my_print_defaults program to parse option files and see what options would be used by a given program. The following example shows the output that my_print_defaults might produce when asked to show the options found in the [client] and [mysql] groups:

shell> my_print_defaults client mysql
--port=3306
--socket=/tmp/mysql.sock
--no-auto-rehash

Note for developers: Option file handling is implemented in the C client library simply by processing all options in the appropriate group or groups before any command-line arguments. This works well for programs that use the last instance of an option that is specified multiple times. If you have a C or C++ program that handles multiply specified options this way but that doesn't read option files, you need add only two lines to give it that capability. Check the source code of any of the standard MySQL clients to see how to do this.

Several other language interfaces to MySQL are based on the C client library, and some of them provide a way to access option file contents. These include Perl and Python. For details, see the documentation for your preferred interface.

4.7.1. msql2mysql — Convert mSQL Programs for Use with MySQL

Initially, the MySQL C API was developed to be very similar to that for the mSQL database system. Because of this, mSQL programs often can be converted relatively easily for use with MySQL by changing the names of the C API functions.

The msql2mysql utility performs the conversion of mSQL C API function calls to their MySQL equivalents. msql2mysql converts the input file in place, so make a copy of the original before converting it. For example, use msql2mysql like this:

shell> cp client-prog.c client-prog.c.orig
shell> msql2mysql client-prog.c
client-prog.c converted

Then examine client-prog.c and make any post-conversion revisions that may be necessary.

msql2mysql uses the replace utility to make the function name substitutions. See Section 4.8.2, “replace — A String-Replacement Utility”.

4.7.2. mysql_config — Get Compile Options for Compiling Clients

mysql_config provides you with useful information for compiling your MySQL client and connecting it to MySQL.

mysql_config supports the following options:

  • --cflags

    Compiler flags to find include files and critical compiler flags and defines used when compiling the libmysqlclient library. The options returned are tied to the specific compiler that was used when the library was created and might clash with the settings for your own compiler. Use --include for more portable options that contain only include paths.

  • --include

    Compiler options to find MySQL include files.

  • --libmysqld-libs, --embedded

    Libraries and options required to link with the MySQL embedded server.

  • --libs

    Libraries and options required to link with the MySQL client library.

  • --libs_r

    Libraries and options required to link with the thread-safe MySQL client library.

  • --plugindir

    The default plugin directory path name, defined when configuring MySQL. This option was added in MySQL 6.0.5.

  • --port

    The default TCP/IP port number, defined when configuring MySQL.

  • --socket

    The default Unix socket file, defined when configuring MySQL.

  • --version

    Version number for the MySQL distribution.

If you invoke mysql_config with no options, it displays a list of all options that it supports, and their values:

shell> mysql_config
Usage: /usr/local/mysql/bin/mysql_config [options]
Options:
  --cflags         [-I/usr/local/mysql/include/mysql -mcpu=pentiumpro]
  --include        [-I/usr/local/mysql/include/mysql]
  --libs           [-L/usr/local/mysql/lib/mysql -lmysqlclient -lz
                    -lcrypt -lnsl -lm -L/usr/lib -lssl -lcrypto]
  --libs_r         [-L/usr/local/mysql/lib/mysql -lmysqlclient_r
                    -lpthread -lz -lcrypt -lnsl -lm -lpthread]
  --socket         [/tmp/mysql.sock]
  --port           [3306]
  --version        [4.0.16]
  --libmysqld-libs [-L/usr/local/mysql/lib/mysql -lmysqld -lpthread -lz
                    -lcrypt -lnsl -lm -lpthread -lrt]

You can use mysql_config within a command line to include the value that it displays for a particular option. For example, to compile a MySQL client program, use mysql_config as follows:

shell> CFG=/usr/local/mysql/bin/mysql_config
shell> sh -c "gcc -o progname `$CFG --include` progname.c `$CFG --libs`"

When you use mysql_config this way, be sure to invoke it within backtick (“`”) characters. That tells the shell to execute it and substitute its output into the surrounding command.

4.7.3. my_print_defaults — Display Options from Option Files

my_print_defaults displays the options that are present in option groups of option files. The output indicates what options will be used by programs that read the specified option groups. For example, the mysqlcheck program reads the [mysqlcheck] and [client] option groups. To see what options are present in those groups in the standard option files, invoke my_print_defaults like this:

shell> my_print_defaults mysqlcheck client
--user=myusername
--password=secret
--host=localhost

The output consists of options, one per line, in the form that they would be specified on the command line.

my_print_defaults supports the following options:

4.7.4. resolve_stack_dump — Resolve Numeric Stack Trace Dump to Symbols

resolve_stack_dump resolves a numeric stack dump to symbols.

Invoke resolve_stack_dump like this:

shell> resolve_stack_dump [options] symbols_file [numeric_dump_file]

The symbols file should include the output from the nm --numeric-sort mysqld command. The numeric dump file should contain a numeric stack track from mysqld. If no numeric dump file is named on the command line, the stack trace is read from the standard input.

resolve_stack_dump supports the options described in the following list.

4.8. Miscellaneous Programs

4.8.1. perror — Explain Error Codes

For most system errors, MySQL displays, in addition to an internal text message, the system error code in one of the following styles:

message ... (errno: #)
message ... (Errcode: #)

You can find out what the error code means by examining the documentation for your system or by using the perror utility.

perror prints a description for a system error code or for a storage engine (table handler) error code.

Invoke perror like this:

shell> perror [options] errorcode ...

Example:

shell> perror 13 64
OS error code  13:  Permission denied
OS error code  64:  Machine is not on the network

Note that the meaning of system error messages may be dependent on your operating system. A given error code may mean different things on different operating systems.

perror supports the following options:

  • --help, --info, -I, -?

    Display a help message and exit.

  • --silent, -s

    Silent mode. Print only the error message.

  • --verbose, -v

    Verbose mode. Print error code and message. This is the default behavior.

  • --version, -V

    Display version information and exit.

4.8.2. replace — A String-Replacement Utility

The replace utility program changes strings in place in files or on the standard input.

Invoke replace in one of the following ways:

shell> replace from to [from to] ... -- file_name [file_name] ...
shell> replace from to [from to] ... < file_name

from represents a string to look for and to represents its replacement. There can be one or more pairs of strings.

Use the -- option to indicate where the string-replacement list ends and the file names begin. In this case, any file named on the command line is modified in place, so you may want to make a copy of the original before converting it. replace prints a message indicating which of the input files it actually modifies.

If the -- option is not given, replace reads the standard input and writes to the standard output.

replace uses a finite state machine to match longer strings first. It can be used to swap strings. For example, the following command swaps a and b in the given files, file1 and file2:

shell> replace a b b a -- file1 file2 ...

The replace program is used by msql2mysql. See Section 4.7.1, “msql2mysql — Convert mSQL Programs for Use with MySQL”.

replace supports the following options:

  • -?, -I

    Display a help message and exit.

  • -#debug_options

    Enable debugging.

  • -s

    Silent mode. Print less information what the program does.

  • -v

    Verbose mode. Print more information about what the program does.

  • -V

    Display version information and exit.

4.8.3. resolveip — Resolve Host name to IP Address or Vice Versa

The resolveip utility resolves host names to IP addresses and vice versa.

Invoke resolveip like this:

shell> resolveip [options] {host_name|ip-addr} ...

resolveip supports the options described in the following list.

  • --help, --info, -?, -I

    Display a help message and exit.

  • --silent, -s

    Silent mode. Produce less output.

  • --version, -V

    Display version information and exit.