pg_lo_read() reads at most
len bytes from a large object and
returns it as a string.
To use the large object interface, it is necessary to enclose it within a transaction block.
Note: This function used to be called pg_loread().
PostgreSQL large object (LOB) resource, returned by pg_lo_open().
An optional maximum number of bytes to return. Defaults to 8192.
A string containing
len bytes from the
large object, or FALSE on error.