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Manual Reference Pages  -  DBLINK_CONNECT (3)

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dblink_connect - opens a persistent connection to a remote database



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


dblink_connect() establishes a connection to a remote PostgreSQL database. The server and database to be contacted are identified through a standard libpq 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 wrapper dblink_fdw when defining the foreign server. See the example below, as well as CREATE SERVER (CREATE_SERVER(7)) and CREATE USER MAPPING (CREATE_USER_MAPPING(7)).



The name to use for this connection; if omitted, an unnamed connection is opened, replacing any existing unnamed connection.


libpq-style connection info string, for example hostaddr= port=5432 dbname=mydb user=postgres password=mypasswd. For details see Section 31.1.1, \(lqConnection Strings\(rq, in the documentation. Alternatively, the name of a foreign server.


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


Only superusers may use dblink_connect to create non-password-authenticated connections. If non-superusers need this capability, use dblink_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 other dblink functions.


SELECT dblink_connect(dbname=postgres);
(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 servers authentication method must be changed.

CREATE SERVER fdtest FOREIGN DATA WRAPPER dblink_fdw OPTIONS (hostaddr, 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_test SELECT 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_USER REVOKE 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;

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PostgreSQL 9.5.2 DBLINK_CONNECT (3) 2016

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