dblink_open - Man Page

dblink_open(text cursorname, text sql [, bool fail_on_error]) returns text
dblink_open(text connname, text cursorname, text sql [, bool fail_on_error]) returns text

dblink_open() opens a cursor in a remote database​. The cursor can subsequently be manipulated with dblink_fetch() and dblink_close()​.

connname

Name of the connection to use; omit this parameter to use the unnamed connection​.

cursorname

The name to assign to this cursor​.

sql

The SELECT statement that you wish to execute in the remote database, for example select * from pg_class​.

fail_on_error

If true (the default when omitted) then an error thrown on the remote side of the connection causes an error to also be thrown locally​. If false, the remote error is locally reported as a NOTICE, and the function's return value is set to ERROR​.

Returns status, either OK or ERROR​.

Since a cursor can only persist within a transaction, dblink_open starts an explicit transaction block (BEGIN) on the remote side, if the remote side was not already within a transaction​. This transaction will be closed again when the matching dblink_close is executed​. Note that if you use dblink_exec to change data between dblink_open and dblink_close, and then an error occurs or you use dblink_disconnect before dblink_close, your change will be lost because the transaction will be aborted​.

SELECT dblink_connect('dbname=postgres options=-csearch_path=');
 dblink_connect
----------------
 OK
(1 row)

SELECT dblink_open('foo', 'select proname, prosrc from pg_proc');
 dblink_open
-------------
 OK
(1 row)