Please apply attached patch to contrib/dblink. It adds named persistent

connections to dblink.

Shridhar Daithanka

contrib/dblink/README.dblink

@@ -4,8 +4,11 @@
  * Functions returning results from a remote database
  *
  * Joe Conway <mail@joeconway.com>
+ * And contributors:
+ * Darko Prenosil <Darko.Prenosil@finteh.hr>
+ * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * Copyright (c) 2001, 2002 by PostgreSQL Global Development Group
+ * Copyright (c) 2001, 2002, 2003 by PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  * 
  * Permission to use, copy, modify, and distribute this software and its
@@ -27,14 +30,16 @@
  *
  */
 
-Version 0.5 (25 August, 2002):
+Version 0.6 (14 June, 2003):
-  Major overhaul to work with new backend "table function" capability. Removed
+  Completely removed previously deprecated functions. Added ability
-  dblink_strtok() and dblink_replace() functions because they are now
+  to create "named" persistent connections in addition to the single global
-  available as backend functions (split() and replace() respectively).
+  "unnamed" persistent connection.
-  Tested under Linux (Red Hat 7.3) and PostgreSQL 7.3devel. This version
+  Tested under Linux (Red Hat 9) and PostgreSQL 7.4devel.
-  is no longer backwards portable to PostgreSQL 7.2.
 
 Release Notes:
+  Version 0.6
+    - functions deprecated in 0.5 have been removed
+    - added ability to create "named" persistent connections
   Version 0.5
     - dblink now supports use directly as a table function; this is the new
       preferred usage going forward
@@ -87,35 +92,51 @@ Installation:
      connection
      ------------
      dblink_connect(text) RETURNS text
-       - opens a connection that will persist for duration of current
+       - opens an unnamed connection that will persist for duration of
+         current backend or until it is disconnected
+     dblink_connect(text,text) RETURNS text
+       - opens a named connection that will persist for duration of current
          backend or until it is disconnected
      dblink_disconnect() RETURNS text
-       - disconnects a persistent connection
+       - disconnects the unnamed persistent connection
+     dblink_disconnect(text) RETURNS text
+       - disconnects a named persistent connection
 
      cursor
      ------------
      dblink_open(text,text) RETURNS text
-       - opens a cursor using connection already opened with dblink_connect()
+       - opens a cursor using unnamed connection already opened with
-         that will persist for duration of current backend or until it is
+         dblink_connect() that will persist for duration of current backend
-         closed
+         or until it is closed
+     dblink_open(text,text,text) RETURNS text
+       - opens a cursor using a named connection already opened with
+         dblink_connect() that will persist for duration of current backend
+         or until it is closed
      dblink_fetch(text, int) RETURNS setof record
-       - fetches data from an already opened cursor
+       - fetches data from an already opened cursor on the unnamed connection
+     dblink_fetch(text, text, int) RETURNS setof record
+       - fetches data from an already opened cursor on a named connection
      dblink_close(text) RETURNS text
-       - closes a cursor
+       - closes a cursor on the unnamed connection
+     dblink_close(text,text) RETURNS text
+       - closes a cursor on a named connection
 
      query
      ------------
      dblink(text,text) RETURNS setof record
-       - returns a set of results from remote SELECT query
+       - returns a set of results from remote SELECT query; the first argument
-         (Note: comment out in dblink.sql to use deprecated version)
+         is either a connection string, or the name of an already opened
+         persistant connection
      dblink(text) RETURNS setof record
-       - returns a set of results from remote SELECT query, using connection
+       - returns a set of results from remote SELECT query, using the unnamed
-         already opened with dblink_connect()
+         connection already opened with dblink_connect()
 
      execute
      ------------
      dblink_exec(text, text) RETURNS text
-       - executes an INSERT/UPDATE/DELETE query remotely
+       - executes an INSERT/UPDATE/DELETE query remotely; the first argument
+         is either a connection string, or the name of an already opened
+         persistant connection
      dblink_exec(text) RETURNS text
        - executes an INSERT/UPDATE/DELETE query remotely, using connection
          already opened with dblink_connect()
@@ -136,19 +157,6 @@ Installation:
        - builds an update statement using a local tuple, replacing the
          selection key field values with alternate supplied values
 
-  Not installed by default
-     deprecated
-     ------------
-     dblink(text,text) RETURNS setof int
-       - *DEPRECATED* returns a resource id for results from remote query
-         (Note: must uncomment in dblink.sql to use)
-     dblink_tok(int,int) RETURNS text
-       - *DEPRECATED* extracts and returns individual field results; used
-         only in conjunction with the *DEPRECATED* form of dblink
-         (Note: must uncomment in dblink.sql to use)
-     dblink_last_oid(int) RETURNS oid
-       - *DEPRECATED* returns the last inserted oid
-
 Documentation:
 
   Note: Parameters representing relation names must include double

contrib/dblink/dblink.h

@@ -4,8 +4,11 @@
  * Functions returning results from a remote database
  *
  * Joe Conway <mail@joeconway.com>
+ * And contributors:
+ * Darko Prenosil <Darko.Prenosil@finteh.hr>
+ * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * Copyright (c) 2001, 2002 by PostgreSQL Global Development Group
+ * Copyright (c) 2001, 2002, 2003 by PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
  * Permission to use, copy, modify, and distribute this software and its
@@ -30,36 +33,9 @@
 #ifndef DBLINK_H
 #define DBLINK_H
 
-/*
- * This struct holds the results of the remote query.
- * Use fn_extra to hold a pointer to it across calls
- */
-typedef struct
-{
-	/*
-	 * last tuple number accessed
-	 */
-	int			tup_num;
-
-	/*
-	 * resource index number for this context
-	 */
-	int			res_id_index;
-
-	/*
-	 * the actual query results
-	 */
-	PGresult   *res;
-}	dblink_results;
-
 /*
  * External declarations
  */
-/* deprecated */
-extern Datum dblink(PG_FUNCTION_ARGS);
-extern Datum dblink_tok(PG_FUNCTION_ARGS);
-
-/* supported */
 extern Datum dblink_connect(PG_FUNCTION_ARGS);
 extern Datum dblink_disconnect(PG_FUNCTION_ARGS);
 extern Datum dblink_open(PG_FUNCTION_ARGS);
@@ -68,7 +44,6 @@ extern Datum dblink_fetch(PG_FUNCTION_ARGS);
 extern Datum dblink_record(PG_FUNCTION_ARGS);
 extern Datum dblink_exec(PG_FUNCTION_ARGS);
 extern Datum dblink_get_pkey(PG_FUNCTION_ARGS);
-extern Datum dblink_last_oid(PG_FUNCTION_ARGS);
 extern Datum dblink_build_sql_insert(PG_FUNCTION_ARGS);
 extern Datum dblink_build_sql_delete(PG_FUNCTION_ARGS);
 extern Datum dblink_build_sql_update(PG_FUNCTION_ARGS);

contrib/dblink/dblink.sql.in

@@ -1,50 +1,53 @@
---
--- Uncomment the following commented lines to use original DEPRECATED functions
---
---CREATE OR REPLACE FUNCTION dblink (text,text)
---RETURNS setof int
---AS 'MODULE_PATHNAME','dblink'
---LANGUAGE 'C' WITH (isstrict);
---CREATE OR REPLACE FUNCTION dblink_tok (int,int)
---RETURNS text
---AS 'MODULE_PATHNAME','dblink_tok'
---LANGUAGE 'C' WITH (isstrict);
---CREATE OR REPLACE FUNCTION dblink_last_oid (int)
---RETURNS oid
---AS 'MODULE_PATHNAME','dblink_last_oid'
---LANGUAGE 'C' WITH (isstrict);
-
 CREATE OR REPLACE FUNCTION dblink_connect (text)
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_connect'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_connect (text, text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_connect'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_disconnect ()
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_disconnect'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_disconnect (text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_disconnect'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_open (text,text)
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_open'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_open (text,text,text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_open'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_fetch (text,int)
 RETURNS setof record
 AS 'MODULE_PATHNAME','dblink_fetch'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_fetch (text,text,int)
+RETURNS setof record
+AS 'MODULE_PATHNAME','dblink_fetch'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_close (text)
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_close'
 LANGUAGE 'C' WITH (isstrict);
 
--- Note: if this is not a first time install of dblink, uncomment the
+CREATE OR REPLACE FUNCTION dblink_close (text,text)
--- following DROP which prepares the database for the new, non-deprecated
+RETURNS text
--- version.
+AS 'MODULE_PATHNAME','dblink_close'
---DROP FUNCTION dblink (text,text);
+LANGUAGE 'C' WITH (isstrict);
 
--- Comment out the following 3 lines if the DEPRECATED functions are used.
 CREATE OR REPLACE FUNCTION dblink (text,text)
 RETURNS setof record
 AS 'MODULE_PATHNAME','dblink_record'

contrib/dblink/doc/connection

@@ -6,21 +6,35 @@ dblink_connect -- Opens a persistent connection to a remote database
 Synopsis
 
 dblink_connect(text connstr)
+dblink_connect(text connname, text connstr)
 
 Inputs
 
+  connname
+    if 2 arguments are given, the first is used as a name for a persistent
+    connection
+
   connstr
 
     standard libpq format connection string, 
     e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
 
+    if only one argument is given, the connection is unnamed; only one unnamed
+    connection can exist at a time
+
 Outputs
 
   Returns status = "OK"
 
 Example usage
 
-test=# select dblink_connect('dbname=template1');
+select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select dblink_connect('myconn','dbname=template1');
  dblink_connect
 ----------------
  OK
@@ -29,15 +43,18 @@ test=# select dblink_connect('dbname=template1');
 ==================================================================
 Name
 
-dblink_disconnect -- Closes the persistent connection to a remote database
+dblink_disconnect -- Closes a persistent connection to a remote database
 
 Synopsis
 
 dblink_disconnect()
+dblink_disconnect(text connname)
 
 Inputs
 
-  none
+  connname
+    if an argument is given, it is used as a name for a persistent
+    connection to close; otherwiase the unnamed connection is closed
 
 Outputs
 
@@ -51,3 +68,8 @@ test=# select dblink_disconnect();
  OK
 (1 row)
 
+select dblink_disconnect('myconn');
+ dblink_disconnect
+-------------------
+ OK
+(1 row)

contrib/dblink/doc/cursor

@@ -6,9 +6,14 @@ dblink_open -- Opens a cursor on a remote database
 Synopsis
 
 dblink_open(text cursorname, text sql)
+dblink_open(text connname, text cursorname, text sql)
 
 Inputs
 
+  connname
+    if three arguments are present, the first is taken as the specific
+    connection name to use; otherwise the unnamed connection is assumed
+
   cursorname
 
     a reference name for the cursor
@@ -52,9 +57,14 @@ dblink_fetch -- Returns a set from an open cursor on a remote database
 Synopsis
 
 dblink_fetch(text cursorname, int32 howmany)
+dblink_fetch(text connname, text cursorname, int32 howmany)
 
 Inputs
 
+  connname
+    if three arguments are present, the first is taken as the specific
+    connection name to use; otherwise the unnamed connection is assumed
+
   cursorname
 
     The reference name for the cursor
@@ -123,9 +133,14 @@ dblink_close -- Closes a cursor on a remote database
 Synopsis
 
 dblink_close(text cursorname)
+dblink_close(text connname, text cursorname)
 
 Inputs
 
+  connname
+    if two arguments are present, the first is taken as the specific
+    connection name to use; otherwise the unnamed connection is assumed
+
   cursorname
 
     a reference name for the cursor
@@ -135,7 +150,8 @@ Outputs
   Returns status = "OK"
 
 Note
-  dblink_connect(text connstr) must be executed first.
+  dblink_connect(text connstr) or dblink_connect(text connname, text connstr)
+  must be executed first.
 
 Example usage
 
@@ -157,3 +173,20 @@ test=# select dblink_close('foo');
  OK
 (1 row)
 
+select dblink_connect('myconn','dbname=regression');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select dblink_open('myconn','foo','select proname, prosrc from pg_proc');
+ dblink_open
+-------------
+ OK
+(1 row)
+
+select dblink_close('myconn','foo');
+ dblink_close
+--------------
+ OK
+(1 row)

contrib/dblink/doc/execute

@@ -6,22 +6,23 @@ dblink_exec -- Executes an UPDATE/INSERT/DELETE on a remote database
 Synopsis
 
 dblink_exec(text connstr, text sql)
-- or -
+dblink_exec(text connname, text sql)
 dblink_exec(text sql)
 
 Inputs
 
+  connname
   connstr
+    If two arguments are present, the first is first assumed to be a specific
+    connection name to use. If the name is not found, the argument is then
+    assumed to be a valid connection string, of standard libpq format,
+    e.g.: "hostaddr=127.0.0.1 dbname=mydb user=postgres password=mypasswd"
 
-    standard libpq format connection string, 
+    If only one argument is used, then the unnamed connection is used.
-    e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
-    If the second form is used, then the dblink_connect(text connstr) must be
-    executed first.
 
   sql
 
     sql statement that you wish to execute on the remote host, e.g.:
-
        insert into foo values(0,'a','{"a0","b0","c0"}');
 
 Outputs
@@ -36,14 +37,26 @@ Notes
 
 Example usage
 
-test=# select dblink_connect('dbname=dblink_test_slave');
+select dblink_connect('dbname=dblink_test_slave');
  dblink_connect
 ----------------
  OK
 (1 row)
 
-test=# select dblink_exec('insert into foo values(21,''z'',''{"a0","b0","c0"}'');');
+select dblink_exec('insert into foo values(21,''z'',''{"a0","b0","c0"}'');');
    dblink_exec
 -----------------
  INSERT 943366 1
 (1 row)
+
+select dblink_connect('myconn','dbname=regression');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select dblink_exec('myconn','insert into foo values(21,''z'',''{"a0","b0","c0"}'');');
+   dblink_exec
+------------------
+ INSERT 6432584 1
+(1 row)

contrib/dblink/doc/query

@@ -6,17 +6,19 @@ dblink -- Returns a set from a remote database
 Synopsis
 
 dblink(text connstr, text sql)
-- or -
+dblink(text connname, text sql)
 dblink(text sql)
 
 Inputs
 
+  connname
   connstr
+    If two arguments are present, the first is first assumed to be a specific
+    connection name to use. If the name is not found, the argument is then
+    assumed to be a valid connection string, of standard libpq format,
+    e.g.: "hostaddr=127.0.0.1 dbname=mydb user=postgres password=mypasswd"
 
-    standard libpq format connection string, 
+    If only one argument is used, then the unnamed connection is used.
-    e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
-    If the second form is used, then the dblink_connect(text connstr) must be
-    executed first.
 
   sql
 
@@ -29,7 +31,7 @@ Outputs
 
 Example usage
 
-test=# select * from dblink('dbname=template1','select proname, prosrc from pg_proc')
+select * from dblink('dbname=template1','select proname, prosrc from pg_proc')
  as t1(proname name, prosrc text) where proname like 'bytea%';
   proname   |   prosrc
 ------------+------------
@@ -47,13 +49,13 @@ test=# select * from dblink('dbname=template1','select proname, prosrc from pg_p
  byteaout   | byteaout
 (12 rows)
 
-test=# select dblink_connect('dbname=template1');
+select dblink_connect('dbname=template1');
  dblink_connect
 ----------------
  OK
 (1 row)
 
-test=# select * from dblink('select proname, prosrc from pg_proc')
+select * from dblink('select proname, prosrc from pg_proc')
  as t1(proname name, prosrc text) where proname like 'bytea%';
   proname   |   prosrc
 ------------+------------
@@ -71,6 +73,33 @@ test=# select * from dblink('select proname, prosrc from pg_proc')
  byteaout   | byteaout
 (12 rows)
 
+select dblink_connect('myconn','dbname=regression');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select * from dblink('myconn','select proname, prosrc from pg_proc')
+ as t1(proname name, prosrc text) where proname like 'bytea%';
+  proname   |   prosrc
+------------+------------
+ bytearecv  | bytearecv
+ byteasend  | byteasend
+ byteale    | byteale
+ byteagt    | byteagt
+ byteage    | byteage
+ byteane    | byteane
+ byteacmp   | byteacmp
+ bytealike  | bytealike
+ byteanlike | byteanlike
+ byteacat   | byteacat
+ byteaeq    | byteaeq
+ bytealt    | bytealt
+ byteain    | byteain
+ byteaout   | byteaout
+(14 rows)
+
+
 ==================================================================
 A more convenient way to use dblink may be to create a view:
 

contrib/dblink/expected/dblink.out

@@ -106,11 +106,11 @@ WHERE t.a > 7;
  9 | j | {a9,b9,c9}
 (2 rows)
 
--- should generate "no connection available" error
+-- should generate "connection not available" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
-ERROR:  dblink: no connection available
+ERROR:  dblink_record: connection not available
 -- create a persistent connection
 SELECT dblink_connect('dbname=regression');
  dblink_connect 
@@ -172,10 +172,10 @@ SELECT dblink_close('rmt_foo_cursor');
  OK
 (1 row)
 
--- should generate "cursor rmt_foo_cursor does not exist" error
+-- should generate "cursor not found: rmt_foo_cursor" error
 SELECT *
 FROM dblink_fetch('rmt_foo_cursor',4) AS t(a int, b text, c text[]);
-ERROR:  dblink_fetch: cursor rmt_foo_cursor does not exist
+ERROR:  dblink_fetch: cursor not found: rmt_foo_cursor
 -- close the persistent connection
 SELECT dblink_disconnect();
  dblink_disconnect 
@@ -183,11 +183,12 @@ SELECT dblink_disconnect();
  OK
 (1 row)
 
--- should generate "no connection available" error
+-- should generate "no connection to the server" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
-ERROR:  dblink: no connection available
+ERROR:  dblink: sql error: no connection to the server
+
 -- put more data into our slave table, first using arbitrary connection syntax
 -- but truncate the actual return value so we can use diff to check for success
 SELECT substr(dblink_exec('dbname=regression','INSERT INTO foo VALUES(10,''k'',''{"a10","b10","c10"}'')'),1,6);
@@ -268,3 +269,198 @@ SELECT dblink_disconnect();
  OK
 (1 row)
 
+--
+-- tests for the new named persistent connection syntax
+--
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ERROR:  dblink: connection error: missing "=" after "myconn" in connection info string
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- use the named persistent connection
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ a  | b |       c       
+----+---+---------------
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+(3 rows)
+
+-- create a second named persistent connection
+-- should error with "cannot save named connection"
+SELECT dblink_connect('myconn','dbname=regression');
+NOTICE:  cannot use a connection name more than once
+ERROR:  dblink_connect: cannot save named connection
+-- create a second named persistent connection with a new name
+SELECT dblink_connect('myconn2','dbname=regression');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- use the second named persistent connection
+SELECT *
+FROM dblink('myconn2','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ a  | b |       c       
+----+---+---------------
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+(3 rows)
+
+-- close the second named persistent connection
+SELECT dblink_disconnect('myconn2');
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- open a cursor
+SELECT dblink_open('myconn','rmt_foo_cursor','SELECT * FROM foo');
+ dblink_open 
+-------------
+ OK
+(1 row)
+
+-- fetch some data
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) 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 rows)
+
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ a | b |     c      
+---+---+------------
+ 4 | e | {a4,b4,c4}
+ 5 | f | {a5,b5,c5}
+ 6 | g | {a6,b6,c6}
+ 7 | h | {a7,b7,c7}
+(4 rows)
+
+-- this one only finds three rows left
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ a  | b |       c       
+----+---+---------------
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+(3 rows)
+
+-- close the cursor
+SELECT dblink_close('myconn','rmt_foo_cursor');
+ dblink_close 
+--------------
+ OK
+(1 row)
+
+-- should generate "cursor not found: rmt_foo_cursor" error
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ERROR:  dblink_fetch: cursor not found: rmt_foo_cursor
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ERROR:  dblink: connection error: missing "=" after "myconn" in connection info string
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- put more data into our slave table, using named persistent connection syntax
+-- but truncate the actual return value so we can use diff to check for success
+SELECT substr(dblink_exec('myconn','INSERT INTO foo VALUES(11,''l'',''{"a11","b11","c11"}'')'),1,6);
+ substr 
+--------
+ INSERT
+(1 row)
+
+-- let's see it
+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 | l | {a11,b11,c11}
+(12 rows)
+
+-- change some data
+SELECT dblink_exec('myconn','UPDATE foo SET f3[2] = ''b99'' WHERE f1 = 11');
+ dblink_exec 
+-------------
+ UPDATE 1
+(1 row)
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+ a  | b |       c       
+----+---+---------------
+ 11 | l | {a11,b99,c11}
+(1 row)
+
+-- delete some data
+SELECT dblink_exec('myconn','DELETE FROM foo WHERE f1 = 11');
+ dblink_exec 
+-------------
+ DELETE 1
+(1 row)
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+ a | b | c 
+---+---+---
+(0 rows)
+
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- close the named persistent connection again
+-- should get "connection named "myconn" not found" error
+SELECT dblink_disconnect('myconn');
+ERROR:  dblink_disconnect: connection named "myconn" not found

contrib/dblink/sql/dblink.sql

@@ -68,7 +68,7 @@ SELECT *
 FROM dblink('dbname=regression','SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
 
--- should generate "no connection available" error
+-- should generate "connection not available" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
@@ -98,14 +98,14 @@ FROM dblink_fetch('rmt_foo_cursor',4) AS t(a int, b text, c text[]);
 -- close the cursor
 SELECT dblink_close('rmt_foo_cursor');
 
--- should generate "cursor rmt_foo_cursor does not exist" error
+-- should generate "cursor not found: rmt_foo_cursor" error
 SELECT *
 FROM dblink_fetch('rmt_foo_cursor',4) AS t(a int, b text, c text[]);
 
 -- close the persistent connection
 SELECT dblink_disconnect();
 
--- should generate "no connection available" error
+-- should generate "no connection to the server" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
@@ -143,3 +143,98 @@ WHERE a = 11;
 
 -- close the persistent connection
 SELECT dblink_disconnect();
+
+--
+-- tests for the new named persistent connection syntax
+--
+
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+
+-- use the named persistent connection
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- create a second named persistent connection
+-- should error with "cannot save named connection"
+SELECT dblink_connect('myconn','dbname=regression');
+
+-- create a second named persistent connection with a new name
+SELECT dblink_connect('myconn2','dbname=regression');
+
+-- use the second named persistent connection
+SELECT *
+FROM dblink('myconn2','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- close the second named persistent connection
+SELECT dblink_disconnect('myconn2');
+
+-- open a cursor
+SELECT dblink_open('myconn','rmt_foo_cursor','SELECT * FROM foo');
+
+-- fetch some data
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+-- this one only finds three rows left
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+-- close the cursor
+SELECT dblink_close('myconn','rmt_foo_cursor');
+
+-- should generate "cursor not found: rmt_foo_cursor" error
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+
+-- put more data into our slave table, using named persistent connection syntax
+-- but truncate the actual return value so we can use diff to check for success
+SELECT substr(dblink_exec('myconn','INSERT INTO foo VALUES(11,''l'',''{"a11","b11","c11"}'')'),1,6);
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]);
+
+-- change some data
+SELECT dblink_exec('myconn','UPDATE foo SET f3[2] = ''b99'' WHERE f1 = 11');
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+
+-- delete some data
+SELECT dblink_exec('myconn','DELETE FROM foo WHERE f1 = 11');
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+
+-- close the named persistent connection again
+-- should get "connection named "myconn" not found" error
+SELECT dblink_disconnect('myconn');