Add missing dblink files.

contrib/dblink/dblink.test.expected.out

@@ -0,0 +1,202 @@
+\connect dblink_test_slave
+create table foo(f1 int, f2 text, f3 text[], primary key (f1,f2));
+NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index 'foo_pkey' for table 'foo'
+insert into foo values(0,'a','{"a0","b0","c0"}');
+insert into foo values(1,'b','{"a1","b1","c1"}');
+insert into foo values(2,'c','{"a2","b2","c2"}');
+insert into foo values(3,'d','{"a3","b3","c3"}');
+insert into foo values(4,'e','{"a4","b4","c4"}');
+insert into foo values(5,'f','{"a5","b5","c5"}');
+insert into foo values(6,'g','{"a6","b6","c6"}');
+insert into foo values(7,'h','{"a7","b7","c7"}');
+insert into foo values(8,'i','{"a8","b8","c8"}');
+insert into foo values(9,'j','{"a9","b9","c9"}');
+\connect dblink_test_master
+-- regular old dblink
+select * from dblink('dbname=dblink_test_slave','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}
+(2 rows)
+
+-- should generate "no connection 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
+-- create a persistent connection
+select dblink_connect('dbname=dblink_test_slave');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- use the persistent connection
+select * from dblink('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}
+(2 rows)
+
+-- open a cursor
+select dblink_open('rmt_foo_cursor','select * from foo');
+ dblink_open 
+-------------
+ OK
+(1 row)
+
+-- fetch some data
+select * from dblink_fetch('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('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 two rows left
+select * from dblink_fetch('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}
+(2 rows)
+
+-- close the cursor
+select dblink_close('rmt_foo_cursor');
+ dblink_close 
+--------------
+ OK
+(1 row)
+
+-- should generate "cursor rmt_foo_cursor does not exist" 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
+-- close the persistent connection
+select dblink_disconnect();
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- should generate "no connection 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
+-- 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=dblink_test_slave','insert into foo values(10,''k'',''{"a10","b10","c10"}'')'),1,6);
+ substr 
+--------
+ INSERT
+(1 row)
+
+-- create a persistent connection
+select dblink_connect('dbname=dblink_test_slave');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- put more data into our slave table, using persistent connection syntax
+-- but truncate the actual return value so we can use diff to check for success
+select substr(dblink_exec('insert into foo values(11,''l'',''{"a11","b11","c11"}'')'),1,6);
+ substr 
+--------
+ INSERT
+(1 row)
+
+-- let's see it
+select * from dblink('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('update foo set f3[2] = ''b99'' where f1 = 11');
+ dblink_exec 
+-------------
+ UPDATE 1
+(1 row)
+
+-- let's see it
+select * from dblink('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('delete from foo where f1 = 11');
+ dblink_exec 
+-------------
+ DELETE 1
+(1 row)
+
+-- let's see it
+select * from dblink('select * from foo') as t(a int, b text, c text[]) where a = 11;
+ a | b | c 
+---+---+---
+(0 rows)
+
+-- misc utilities
+\connect dblink_test_slave
+-- show the currently executing query
+select 'hello' as hello, dblink_current_query() as query;
+ hello |                           query                           
+-------+-----------------------------------------------------------
+ hello | select 'hello' as hello, dblink_current_query() as query;
+(1 row)
+
+-- list the primary key fields
+select * from dblink_get_pkey('foo');
+ position | colname 
+----------+---------
+        1 | f1
+        2 | f2
+(2 rows)
+
+-- build an insert statement based on a local tuple,
+-- replacing the primary key values with new ones
+select dblink_build_sql_insert('foo','1 2',2,'{"0", "a"}','{"99", "xyz"}');
+                  dblink_build_sql_insert                  
+-----------------------------------------------------------
+ INSERT INTO foo(f1,f2,f3) VALUES('99','xyz','{a0,b0,c0}')
+(1 row)
+
+-- build an update statement based on a local tuple,
+-- replacing the primary key values with new ones
+select dblink_build_sql_update('foo','1 2',2,'{"0", "a"}','{"99", "xyz"}');
+                                dblink_build_sql_update                                 
+----------------------------------------------------------------------------------------
+ UPDATE foo SET f1 = '99', f2 = 'xyz', f3 = '{a0,b0,c0}' WHERE f1 = '99' AND f2 = 'xyz'
+(1 row)
+
+-- build a delete statement based on a local tuple,
+select dblink_build_sql_delete('foo','1 2',2,'{"0", "a"}');
+           dblink_build_sql_delete           
+---------------------------------------------
+ DELETE FROM foo WHERE f1 = '0' AND f2 = 'a'
+(1 row)
+

contrib/dblink/dblink.test.sql

@@ -0,0 +1,95 @@
+\connect dblink_test_slave
+
+create table foo(f1 int, f2 text, f3 text[], primary key (f1,f2));
+insert into foo values(0,'a','{"a0","b0","c0"}');
+insert into foo values(1,'b','{"a1","b1","c1"}');
+insert into foo values(2,'c','{"a2","b2","c2"}');
+insert into foo values(3,'d','{"a3","b3","c3"}');
+insert into foo values(4,'e','{"a4","b4","c4"}');
+insert into foo values(5,'f','{"a5","b5","c5"}');
+insert into foo values(6,'g','{"a6","b6","c6"}');
+insert into foo values(7,'h','{"a7","b7","c7"}');
+insert into foo values(8,'i','{"a8","b8","c8"}');
+insert into foo values(9,'j','{"a9","b9","c9"}');
+
+\connect dblink_test_master
+
+-- regular old dblink
+select * from dblink('dbname=dblink_test_slave','select * from foo') as t(a int, b text, c text[]) where t.a > 7;
+
+-- should generate "no connection available" error
+select * from dblink('select * from foo') as t(a int, b text, c text[]) where t.a > 7;
+
+-- create a persistent connection
+select dblink_connect('dbname=dblink_test_slave');
+
+-- use the persistent connection
+select * from dblink('select * from foo') as t(a int, b text, c text[]) where t.a > 7;
+
+-- open a cursor
+select dblink_open('rmt_foo_cursor','select * from foo');
+
+-- fetch some data
+select * from dblink_fetch('rmt_foo_cursor',4) as t(a int, b text, c text[]);
+select * from dblink_fetch('rmt_foo_cursor',4) as t(a int, b text, c text[]);
+
+-- this one only finds two rows left
+select * 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
+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
+select * from dblink('select * from foo') as t(a int, b text, c text[]) where t.a > 7;
+
+-- 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=dblink_test_slave','insert into foo values(10,''k'',''{"a10","b10","c10"}'')'),1,6);
+
+-- create a persistent connection
+select dblink_connect('dbname=dblink_test_slave');
+
+-- put more data into our slave table, using persistent connection syntax
+-- but truncate the actual return value so we can use diff to check for success
+select substr(dblink_exec('insert into foo values(11,''l'',''{"a11","b11","c11"}'')'),1,6);
+
+-- let's see it
+select * from dblink('select * from foo') as t(a int, b text, c text[]);
+
+-- change some data
+select dblink_exec('update foo set f3[2] = ''b99'' where f1 = 11');
+
+-- let's see it
+select * from dblink('select * from foo') as t(a int, b text, c text[]) where a = 11;
+
+-- delete some data
+select dblink_exec('delete from foo where f1 = 11');
+
+-- let's see it
+select * from dblink('select * from foo') as t(a int, b text, c text[]) where a = 11;
+
+-- misc utilities
+\connect dblink_test_slave
+
+-- show the currently executing query
+select 'hello' as hello, dblink_current_query() as query;
+
+-- list the primary key fields
+select * from dblink_get_pkey('foo');
+
+-- build an insert statement based on a local tuple,
+-- replacing the primary key values with new ones
+select dblink_build_sql_insert('foo','1 2',2,'{"0", "a"}','{"99", "xyz"}');
+
+-- build an update statement based on a local tuple,
+-- replacing the primary key values with new ones
+select dblink_build_sql_update('foo','1 2',2,'{"0", "a"}','{"99", "xyz"}');
+
+-- build a delete statement based on a local tuple,
+select dblink_build_sql_delete('foo','1 2',2,'{"0", "a"}');

contrib/dblink/dblink_check.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+dropdb -U postgres dblink_test_master
+createdb -U postgres dblink_test_master
+psql -U postgres dblink_test_master < `pwd`/dblink.sql
+
+dropdb -U postgres dblink_test_slave
+createdb -U postgres dblink_test_slave
+psql -U postgres dblink_test_slave < `pwd`/dblink.sql
+
+psql -eaq -U postgres template1 < `pwd`/dblink.test.sql > dblink.test.out 2>&1
+diff -c ./dblink.test.expected.out `pwd`/dblink.test.out > dblink.test.diff
+ls -l dblink.test.diff
+
+

contrib/dblink/doc/connection

@@ -0,0 +1,53 @@
+==================================================================
+Name
+
+dblink_connect -- Opens a persistent connection to a remote database
+
+Synopsis
+
+dblink_connect(text connstr)
+
+Inputs
+
+  connstr
+
+    standard libpq format connection string, 
+    e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
+
+Outputs
+
+  Returns status = "OK"
+
+Example usage
+
+test=# select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+==================================================================
+Name
+
+dblink_disconnect -- Closes the persistent connection to a remote database
+
+Synopsis
+
+dblink_disconnect()
+
+Inputs
+
+  none
+
+Outputs
+
+  Returns status = "OK"
+
+Example usage
+
+test=# select dblink_disconnect();
+ dblink_disconnect
+-------------------
+ OK
+(1 row)
+

contrib/dblink/doc/cursor

@@ -0,0 +1,159 @@
+==================================================================
+Name
+
+dblink_open -- Opens a cursor on a remote database
+
+Synopsis
+
+dblink_open(text cursorname, text sql)
+
+Inputs
+
+  cursorname
+
+    a reference name for the cursor
+
+  sql
+
+    sql statement that you wish to execute on the remote host
+    e.g. "select * from pg_class"
+
+Outputs
+
+  Returns status = "OK"
+
+Note
+  1) dblink_connect(text connstr) must be executed first
+  2) dblink_open starts an explicit transaction. If, after using dblink_open,
+     you use dblink_exec to change data, and then an error occurs or you use
+     dblink_disconnect without a dblink_close first, your change *will* be
+     lost. Also, using dblink_close explicitly ends the transaction and thus
+     effectively closes *all* open cursors.
+
+Example usage
+
+test=# select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+test=# select dblink_open('foo','select proname, prosrc from pg_proc');
+ dblink_open
+-------------
+ OK
+(1 row)
+
+==================================================================
+Name
+
+dblink_fetch -- Returns a set from an open cursor on a remote database
+
+Synopsis
+
+dblink_fetch(text cursorname, int32 howmany)
+
+Inputs
+
+  cursorname
+
+    The reference name for the cursor
+
+  howmany
+
+    Maximum number of rows to retrieve. The next howmany rows are fetched,
+    starting at the current cursor position, moving forward. Once the cursor
+    has positioned to the end, no more rows are produced.
+
+Outputs
+
+  Returns setof record
+
+Example usage
+
+test=# select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+test=# select dblink_open('foo','select proname, prosrc from pg_proc where proname like ''bytea%''');
+ dblink_open
+-------------
+ OK
+(1 row)
+
+test=# select * from dblink_fetch('foo',5) as (funcname name, source text);
+ funcname |  source
+----------+----------
+ byteacat | byteacat
+ byteacmp | byteacmp
+ byteaeq  | byteaeq
+ byteage  | byteage
+ byteagt  | byteagt
+(5 rows)
+
+test=# select * from dblink_fetch('foo',5) as (funcname name, source text);
+ funcname  |  source
+-----------+-----------
+ byteain   | byteain
+ byteale   | byteale
+ bytealike | bytealike
+ bytealt   | bytealt
+ byteane   | byteane
+(5 rows)
+
+test=# select * from dblink_fetch('foo',5) as (funcname name, source text);
+  funcname  |   source
+------------+------------
+ byteanlike | byteanlike
+ byteaout   | byteaout
+(2 rows)
+
+test=# select * from dblink_fetch('foo',5) as (funcname name, source text);
+ funcname | source
+----------+--------
+(0 rows)
+
+==================================================================
+Name
+
+dblink_close -- Closes a cursor on a remote database
+
+Synopsis
+
+dblink_close(text cursorname)
+
+Inputs
+
+  cursorname
+
+    a reference name for the cursor
+
+Outputs
+
+  Returns status = "OK"
+
+Note
+  dblink_connect(text connstr) must be executed first.
+
+Example usage
+
+test=# select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+test=# select dblink_open('foo','select proname, prosrc from pg_proc');
+ dblink_open
+-------------
+ OK
+(1 row)
+
+test=# select dblink_close('foo');
+ dblink_close
+--------------
+ OK
+(1 row)
+

contrib/dblink/doc/deprecated

@@ -0,0 +1,105 @@
+==================================================================
+Name
+
+*DEPRECATED* use new dblink syntax
+dblink -- Returns a resource id for a data set from a remote database
+
+Synopsis
+
+dblink(text connstr, text sql)
+
+Inputs
+
+  connstr
+
+    standard libpq format connection srting, 
+    e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
+
+  sql
+
+    sql statement that you wish to execute on the remote host
+    e.g. "select * from pg_class"
+
+Outputs
+
+  Returns setof int (res_id)
+
+Example usage
+
+  select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
+               ,'select f1, f2 from mytable');
+
+==================================================================
+
+Name
+
+*DEPRECATED* use new dblink syntax
+dblink_tok -- Returns individual select field results from a dblink remote query
+
+Synopsis
+
+dblink_tok(int res_id, int fnumber)
+
+Inputs
+
+  res_id
+
+    a resource id returned by a call to dblink()
+
+  fnumber
+
+    the ordinal position (zero based) of the field to be returned from the dblink result set
+
+Outputs
+
+  Returns text
+
+Example usage
+
+  select dblink_tok(t1.dblink_p,0) as f1, dblink_tok(t1.dblink_p,1) as f2
+  from (select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
+                     ,'select f1, f2 from mytable') as dblink_p) as t1;
+
+
+==================================================================
+*DEPRECATED* use new dblink syntax
+A more convenient way to use dblink may be to create a view:
+
+ create view myremotetable as
+ select dblink_tok(t1.dblink_p,0) as f1, dblink_tok(t1.dblink_p,1) as f2
+ from (select dblink('hostaddr=127.0.0.1 port=5432 dbname=template1 user=postgres password=postgres'
+                    ,'select proname, prosrc from pg_proc') as dblink_p) as t1;
+
+Then you can simply write:
+
+   select f1, f2 from myremotetable where f1 like 'bytea%';
+
+==================================================================
+Name
+*DEPRECATED* use new dblink_exec syntax
+dblink_last_oid -- Returns last inserted oid
+
+Synopsis
+
+dblink_last_oid(int res_id) RETURNS oid
+
+Inputs
+
+  res_id
+
+    any resource id returned by dblink function;
+
+Outputs
+
+  Returns oid of last inserted tuple
+
+Example usage
+
+test=# select dblink_last_oid(dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
+               ,'insert into mytable (f1, f2) values (1,2)'));
+
+ dblink_last_oid
+----------------
+ 16553
+(1 row)
+

contrib/dblink/doc/execute

@@ -0,0 +1,49 @@
+==================================================================
+Name
+
+dblink_exec -- Executes an UPDATE/INSERT/DELETE on a remote database
+
+Synopsis
+
+dblink_exec(text connstr, text sql)
+- or -
+dblink_exec(text sql)
+
+Inputs
+
+  connstr
+
+    standard libpq format connection string, 
+    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
+
+  Returns status of the command
+
+Notes
+  1) dblink_open starts an explicit transaction. If, after using dblink_open,
+     you use dblink_exec to change data, and then an error occurs or you use
+     dblink_disconnect without a dblink_close first, your change *will* be
+     lost.
+
+Example usage
+
+test=# 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"}'');');
+   dblink_exec
+-----------------
+ INSERT 943366 1
+(1 row)

contrib/dblink/doc/misc

@@ -0,0 +1,140 @@
+==================================================================
+Name
+
+dblink_current_query -- returns the current query string
+
+Synopsis
+
+dblink_current_query () RETURNS text
+
+Inputs
+
+  None
+
+Outputs
+
+  Returns text -- a copy of the currently executing query
+
+Example usage
+
+test=# select dblink_current_query() from (select dblink('dbname=template1','select oid, proname from pg_proc where proname = ''byteacat''') as f1) as t1;
+                                                                dblink_current_query
+-----------------------------------------------------------------------------------------------------------------------------------------------------
+ select dblink_current_query() from (select dblink('dbname=template1','select oid, proname from pg_proc where proname = ''byteacat''') as f1) as t1;
+(1 row)
+
+==================================================================
+Name
+
+dblink_get_pkey -- returns the position and field names of a relation's
+                   primary key fields
+
+Synopsis
+
+dblink_get_pkey(text relname) RETURNS setof dblink_pkey_results
+
+Inputs
+
+  relname
+
+    any relation name;
+    e.g. 'foobar'
+
+Outputs
+
+  Returns setof dblink_pkey_results -- one row for each primary key field,
+    in order of position in the key. dblink_pkey_results is defined as follows:
+       CREATE TYPE dblink_pkey_results AS (position int4, colname text);
+
+Example usage
+
+test=# select * from dblink_get_pkey('foobar');
+ position | colname
+----------+---------
+        1 | f1
+        2 | f2
+        3 | f3
+        4 | f4
+        5 | f5
+
+==================================================================
+Name
+
+dblink_build_sql_insert -- builds an insert statement using a local
+                           tuple, replacing the selection key field
+                           values with alternate supplied values
+dblink_build_sql_delete -- builds a delete statement using supplied
+                           values for selection key field values
+dblink_build_sql_update -- builds an update statement using a local
+                           tuple, replacing the selection key field
+                           values with alternate supplied values
+
+
+Synopsis
+
+dblink_build_sql_insert(text relname
+                         ,int2vector primary_key_attnums
+                         ,int2 num_primary_key_atts
+                         ,_text src_pk_att_vals_array
+                         ,_text tgt_pk_att_vals_array) RETURNS text
+dblink_build_sql_delete(text relname
+                         ,int2vector primary_key_attnums
+                         ,int2 num_primary_key_atts
+                         ,_text tgt_pk_att_vals_array) RETURNS text
+dblink_build_sql_update(text relname
+                         ,int2vector primary_key_attnums
+                         ,int2 num_primary_key_atts
+                         ,_text src_pk_att_vals_array
+                         ,_text tgt_pk_att_vals_array) RETURNS text
+
+Inputs
+
+  relname
+
+    any relation name;
+    e.g. 'foobar'
+
+  primary_key_attnums
+
+    vector of primary key attnums (1 based, see pg_index.indkey);
+    e.g. '1 2'
+
+  num_primary_key_atts
+
+    number of primary key attnums in the vector; e.g. 2
+
+  src_pk_att_vals_array
+
+    array of primary key values, used to look up the local matching
+    tuple, the values of which are then used to construct the SQL
+    statement
+
+  tgt_pk_att_vals_array
+
+    array of primary key values, used to replace the local tuple
+    values in the SQL statement
+
+Outputs
+
+  Returns text -- requested SQL statement
+
+Example usage
+
+test=# select dblink_build_sql_insert('foo','1 2',2,'{"1", "a"}','{"1", "b''a"}');
+             dblink_build_sql_insert
+--------------------------------------------------
+ INSERT INTO foo(f1,f2,f3) VALUES('1','b''a','1')
+(1 row)
+
+test=# select dblink_build_sql_delete('MyFoo','1 2',2,'{"1", "b"}');
+           dblink_build_sql_delete
+---------------------------------------------
+ DELETE FROM "MyFoo" WHERE f1='1' AND f2='b'
+(1 row)
+
+test=# select dblink_build_sql_update('foo','1 2',2,'{"1", "a"}','{"1", "b"}');
+                   dblink_build_sql_update
+-------------------------------------------------------------
+ UPDATE foo SET f1='1',f2='b',f3='1' WHERE f1='1' AND f2='b'
+(1 row)
+

contrib/dblink/doc/query

@@ -0,0 +1,85 @@
+==================================================================
+Name
+
+dblink -- Returns a set from a remote database
+
+Synopsis
+
+dblink(text connstr, text sql)
+- or -
+dblink(text sql)
+
+Inputs
+
+  connstr
+
+    standard libpq format connection string, 
+    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. "select * from pg_class"
+
+Outputs
+
+  Returns setof record
+
+Example usage
+
+test=# select * from dblink('dbname=template1','select proname, prosrc from pg_proc')
+ as t1(proname name, prosrc text) where proname like 'bytea%';
+  proname   |   prosrc
+------------+------------
+ byteacat   | byteacat
+ byteaeq    | byteaeq
+ bytealt    | bytealt
+ byteale    | byteale
+ byteagt    | byteagt
+ byteage    | byteage
+ byteane    | byteane
+ byteacmp   | byteacmp
+ bytealike  | bytealike
+ byteanlike | byteanlike
+ byteain    | byteain
+ byteaout   | byteaout
+(12 rows)
+
+test=# select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+test=# select * from dblink('select proname, prosrc from pg_proc')
+ as t1(proname name, prosrc text) where proname like 'bytea%';
+  proname   |   prosrc
+------------+------------
+ byteacat   | byteacat
+ byteaeq    | byteaeq
+ bytealt    | bytealt
+ byteale    | byteale
+ byteagt    | byteagt
+ byteage    | byteage
+ byteane    | byteane
+ byteacmp   | byteacmp
+ bytealike  | bytealike
+ byteanlike | byteanlike
+ byteain    | byteain
+ byteaout   | byteaout
+(12 rows)
+
+==================================================================
+A more convenient way to use dblink may be to create a view:
+
+ create view myremote_pg_proc as
+ select *
+ from dblink('dbname=template1','select proname, prosrc from pg_proc')
+ as t1(proname name, prosrc text);
+
+Then you can simply write:
+
+   select * from myremote_pg_proc where proname like 'bytea%';
+