Name

Synopsis

dblink_connect(text connstr) returns textdblink_connect(text connname, text connstr) returns text

Description

dblink_connect() establishes a connection to a remotePostgreSQL database. The server and database to be contacted are identified through a standardlibpq connection string. Optionally, a name can be assigned to the connection. Multiple named connections can be open at once, but only one unnamed connection is permitted at a time. The connection will persist until closed or until the database session is ended.

The connection string may also be the name of an existing foreign server. It is recommended to use the foreign-data wrapperdblink_fdw when defining the foreign server. See the example below, as well asCREATE SERVER andCREATE USER MAPPING.

Arguments

Return Value

Returns status, which is alwaysOK (since any error causes the function to throw an error instead of returning).

Notes

Only superusers may usedblink_connect to create non-password-authenticated connections. If non-superusers need this capability, usedblink_connect_u instead.

It is unwise to choose connection names that contain equal signs, as this opens a risk of confusion with connection info strings in otherdblink functions.

Examples

SELECT dblink_connect('dbname=postgres'); dblink_connect---------------- OK(1 row)SELECT dblink_connect('myconn', 'dbname=postgres'); dblink_connect---------------- OK(1 row)-- FOREIGN DATA WRAPPER functionality-- Note: local connection must require password authentication for this to work properly--       Otherwise, you will receive the following error from dblink_connect():--       ------------------------------------------------------------------------       ERROR:  password is required--       DETAIL:  Non-superuser cannot connect if the server does not request a password.--       HINT:  Target server's authentication method must be changed.CREATE SERVER fdtest FOREIGN DATA WRAPPER dblink_fdw OPTIONS (hostaddr '127.0.0.1', dbname 'contrib_regression');CREATE USER dblink_regression_test WITH PASSWORD 'secret';CREATE USER MAPPING FOR dblink_regression_test SERVER fdtest OPTIONS (user 'dblink_regression_test', password 'secret');GRANT USAGE ON FOREIGN SERVER fdtest TO dblink_regression_test;GRANT SELECT ON TABLE foo TO dblink_regression_test;\set ORIGINAL_USER :USER\c - dblink_regression_testSELECT dblink_connect('myconn', 'fdtest'); dblink_connect ---------------- OK(1 row)SELECT * FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]); a  | b |       c       ----+---+---------------  0 | a | {a0,b0,c0}  1 | b | {a1,b1,c1}  2 | c | {a2,b2,c2}  3 | d | {a3,b3,c3}  4 | e | {a4,b4,c4}  5 | f | {a5,b5,c5}  6 | g | {a6,b6,c6}  7 | h | {a7,b7,c7}  8 | i | {a8,b8,c8}  9 | j | {a9,b9,c9} 10 | k | {a10,b10,c10}(11 rows)\c - :ORIGINAL_USERREVOKE USAGE ON FOREIGN SERVER fdtest FROM dblink_regression_test;REVOKE SELECT ON TABLE foo FROM dblink_regression_test;DROP USER MAPPING FOR dblink_regression_test SERVER fdtest;DROP USER dblink_regression_test;DROP SERVER fdtest;