44.3. pg_am

The catalog pg_am stores information about index access methods. There is one row for each index access method supported by the system. The contents of this catalog are discussed in detail in Chapter 50.

Table 44-3. pg_am Columns

amnamename Name of the access method
amstrategiesint2 Number of operator strategies for this access method, or zero if access method does not have a fixed set of operator strategies
amsupportint2 Number of support routines for this access method
amcanorderbool Does the access method support ordered scans?
amcanuniquebool Does the access method support unique indexes?
amcanmulticolbool Does the access method support multicolumn indexes?
amoptionalkeybool Does the access method support a scan without any constraint for the first index column?
amindexnullsbool Does the access method support null index entries?
amsearchnullsbool Does the access method support IS NULL searches?
amstoragebool Can index storage data type differ from column data type?
amclusterablebool Can an index of this type be clustered on?
aminsertregprocpg_proc.oid"Insert this tuple" function
ambeginscanregprocpg_proc.oid"Start new scan" function
amgettupleregprocpg_proc.oid"Next valid tuple" function
amgetmultiregprocpg_proc.oid"Fetch multiple tuples" function
amrescanregprocpg_proc.oid"Restart this scan" function
amendscanregprocpg_proc.oid"End this scan" function
ammarkposregprocpg_proc.oid"Mark current scan position" function
amrestrposregprocpg_proc.oid"Restore marked scan position" function
ambuildregprocpg_proc.oid"Build new index" function
ambulkdeleteregprocpg_proc.oidBulk-delete function
amvacuumcleanupregprocpg_proc.oidPost-VACUUM cleanup function
amcostestimateregprocpg_proc.oidFunction to estimate cost of an index scan
amoptionsregprocpg_proc.oidFunction to parse and validate reloptions for an index