Chapter 29. pgtcl - Tcl Binding Library

Table of Contents

29.2. Loading pgtcl into an Application

pg_connect -- open a connection to the server
pg_disconnect -- close a connection to the server
pg_conndefaults -- get connection options and their defaults
pg_exec -- send a command to the server
pg_result -- get information about a command result
pg_select -- loop over the result of a query
pg_execute -- send a query and optionally loop over the results
pg_listen -- set or change a callback for asynchronous notification messages
pg_on_connection_loss -- set or change a callback for unexpected connection loss
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 from a large object
pg_lo_write -- write to a large object
pg_lo_lseek -- seek to a position of 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 large object from a file
pg_lo_export -- export a large object to a file

pgtcl is a Tcl package for client programs to interface with PostgreSQL servers. It makes most of the functionality of libpq available to Tcl scripts.

29.1. Overview

Table 29-1 gives an overview over the commands available in pgtcl. These commands are described further on subsequent pages.

Table 29-1. pgtcl Commands

Command	Description
`pg_connect`	open a connection to the server
`pg_disconnect`	close a connection to the server
`pg_conndefaults`	get connection options and their defaults
`pg_exec`	send a command to the server
`pg_result`	get information about a command result
`pg_select`	loop over the result of a query
`pg_execute`	send a query and optionally loop over the results
`pg_listen`	set or change a callback for asynchronous notification messages
`pg_on_connection_loss`	set or change a callback for unexpected connection loss
`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 from a large object
`pg_lo_write`	write to a large object
`pg_lo_lseek`	seek to a position in 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 large object from a file
`pg_lo_export`	export a large object to a file

The pg_lo_* commands are interfaces to the large object features of PostgreSQL. The functions are designed to mimic the analogous file system functions in the standard Unix file system interface. The pg_lo_* commands should be used within a BEGIN/COMMIT transaction block because the 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/COMMIT transaction block.