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The pg_lo* routines are interfaces to the Inversion Large Objects in Postgres. The functions are designed to mimic the analogous file system functions in the standard Unix file system interface.

Table 45-1. PGTCL Commands

Command Description
pg_connect opens a connection to the backend server
pg_disconnect closes a connection
pg_exec send a query to the backend
pg_select loop over the result of a select statement
pg_result manipulate the results of a query
pg_lo_creat create a large object
pg_lo_open open a large object
pg_lo_close close a large object
pg_lo_read read a large object
pg_lo_write write a large object
pg_lo_lseek seek to a position on a large object
pg_lo_tell return the current seek position of a large object
pg_lo_unlink delete a large object
pg_lo_import import a Unix file into a large object
pg_lo_export export a large object into a Unix file

Some commands equivalent to libpq commands are provided for connection and query operations.

The pg_lo* routines should typically be used within a BEGIN/END transaction block because the file descriptor returned by pg_lo_open is only valid for the current transaction. pg_lo_import and pg_lo_export MUST be used in a BEGIN/END transaction block.

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