NAME

       dblink_connect - opens a persistent connection to a remote database

SYNOPSIS

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

DESCRIPTION

           Note
           The following description applies only to Postgres-XC

       dblink module has not been tested with Postges-XC yet. Although there're no reason that
       dblink does not run in Postgres-XC, the development team leaves the test and the use of
       this module entirely to users.

       This section is identical to the corresponding PostgreSQL reference manual.

           Note
           The following description applies only to PostgreSQL

       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 postgresql_fdw_validator when defining the corresponding
       foreign-data wrapper. See the example below, as well as the following: CREATE FOREIGN DATA
       WRAPPER (CREATE_FOREIGN_DATA_WRAPPER(7)), CREATE SERVER (CREATE_SERVER(7)), CREATE USER
       MAPPING (CREATE_USER_MAPPING(7))

ARGUMENTS

           Note
           The following description applies only to Postgres-XC

       dblink module has not been tested with Postges-XC yet. Although there're no reason that
       dblink does not run in Postgres-XC, the development team leaves the test and the use of
       this module entirely to users.

       This section is identical to the corresponding PostgreSQL reference manual.

           Note
           The following description applies only to PostgreSQL

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

       connstr
           libpq-style connection info string, for example hostaddr=127.0.0.1 port=5432
           dbname=mydb user=postgres password=mypasswd. For details see PQconnectdb in Section
           32.1, “Database Connection Control Functions”, in the documentation.

RETURN VALUE

           Note
           The following description applies only to Postgres-XC

       dblink module has not been tested with Postges-XC yet. Although there're no reason that
       dblink does not run in Postgres-XC, the development team leaves the test and the use of
       this module entirely to users.

       This section is identical to the corresponding PostgreSQL reference manual.

           Note
           The following description applies only to PostgreSQL

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

NOTES

           Note
           The following description applies only to Postgres-XC

       dblink module has not been tested with Postges-XC yet. Although there're no reason that
       dblink does not run in Postgres-XC, the development team leaves the test and the use of
       this module entirely to users.

       This section is identical to the corresponding PostgreSQL reference manual.

           Note
           The following description applies only to PostgreSQL

       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.

EXAMPLES

           Note
           The following description applies only to Postgres-XC

       dblink module has not been tested with Postges-XC yet. Although there're no reason that
       dblink does not run in Postgres-XC, the development team leaves the test and the use of
       this module entirely to users.

       This section is identical to the corresponding PostgreSQL reference manual.

           Note
           The following description applies only to PostgreSQL

           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 USER dblink_regression_test WITH PASSWORD 'secret';
           CREATE FOREIGN DATA WRAPPER postgresql VALIDATOR postgresql_fdw_validator;
           CREATE SERVER fdtest FOREIGN DATA WRAPPER postgresql OPTIONS (hostaddr '127.0.0.1', dbname 'contrib_regression');

           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;
           DROP FOREIGN DATA WRAPPER postgresql;