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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
|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.