/*
* dblink
*
* 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) 2001-2005, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose, without fee, and without a written agreement
* is hereby granted, provided that the above copyright notice and this
* paragraph and the following two paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
*/
Release Notes:
Version 0.7 (as of 25 Feb, 2004)
- Added new version of dblink, dblink_exec, dblink_open, dblink_close,
and, dblink_fetch -- allows ERROR on remote side of connection to
throw NOTICE locally instead of ERROR
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
- Use of dblink_tok is now deprecated; original form of dblink is also
deprecated. They _will_ be removed in the next version.
- dblink_last_oid is also deprecated; use dblink_exec() which returns
the command status as a single row, single column result.
- Original dblink, dblink_tok, and dblink_last_oid are commented out in
dblink.sql; remove the comments to use the deprecated functions.
- dblink_strtok() and dblink_replace() functions were removed. Use
split() and replace() respectively (new backend functions in
PostgreSQL 7.3) instead.
- New functions: dblink_exec() for non-SELECT queries; dblink_connect()
opens connection that persists for duration of a backend;
dblink_disconnect() closes a persistent connection; dblink_open()
opens a cursor; dblink_fetch() fetches results from an open cursor.
dblink_close() closes a cursor.
- New test suite: dblink_check.sh, dblink.test.sql,
dblink.test.expected.out. Execute dblink_check.sh from the same
directory as the other two files. Output is dblink.test.out and
dblink.test.diff. Note that dblink.test.sql is a good source
of example usage.
Version 0.4
- removed cursor wrap around input sql to allow for remote
execution of INSERT/UPDATE/DELETE
- dblink now returns a resource id instead of a real pointer
- added several utility functions -- see below
Version 0.3
- fixed dblink invalid pointer causing corrupt elog message
- fixed dblink_tok improper handling of null results
- fixed examples in README.dblink
Version 0.2
- initial release
Installation:
Place these files in a directory called 'dblink' under 'contrib' in the PostgreSQL source tree. Then run:
make
make install
You can use dblink.sql to create the functions in your database of choice, e.g.
psql template1 < dblink.sql
installs following functions into database template1:
connection
------------
dblink_connect(text) RETURNS text
- 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 the unnamed persistent connection
dblink_disconnect(text) RETURNS text
- disconnects a named persistent connection
cursor
------------
dblink_open(text,text [, bool fail_on_error]) RETURNS text
- opens a cursor using unnamed connection already opened with
dblink_connect() that will persist for duration of current backend
or until it is closed
dblink_open(text,text,text [, bool fail_on_error]) 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 [, bool fail_on_error]) RETURNS setof record
- fetches data from an already opened cursor on the unnamed connection
dblink_fetch(text, text, int [, bool fail_on_error]) RETURNS setof record
- fetches data from an already opened cursor on a named connection
dblink_close(text [, bool fail_on_error]) RETURNS text
- closes a cursor on the unnamed connection
dblink_close(text,text [, bool fail_on_error]) RETURNS text
- closes a cursor on a named connection
query
------------
dblink(text,text [, bool fail_on_error]) RETURNS setof record
- returns a set of results from remote SELECT query; the first argument
is either a connection string, or the name of an already opened
persistant connection
dblink(text [, bool fail_on_error]) RETURNS setof record
- returns a set of results from remote SELECT query, using the unnamed
connection already opened with dblink_connect()
execute
------------
dblink_exec(text, text [, bool fail_on_error]) RETURNS text
- 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 [, bool fail_on_error]) RETURNS text
- executes an INSERT/UPDATE/DELETE query remotely, using connection
already opened with dblink_connect()
misc
------------
dblink_current_query() RETURNS text
- returns the current query string
dblink_get_pkey(text) RETURNS setof text
- returns the field names of a relation's primary key fields
dblink_build_sql_insert(text,int2vector,int2,_text,_text) RETURNS text
- builds an insert statement using a local tuple, replacing the
selection key field values with alternate supplied values
dblink_build_sql_delete(text,int2vector,int2,_text) RETURNS text
- builds a delete statement using supplied values for selection
key field values
dblink_build_sql_update(text,int2vector,int2,_text,_text) RETURNS text
- builds an update statement using a local tuple, replacing the
selection key field values with alternate supplied values
Documentation:
Note: Parameters representing relation names must include double
quotes if the names are mixed-case or contain special characters. They
must also be appropriately qualified with schema name if applicable.
See the following files:
doc/connection
doc/cursor
doc/query
doc/execute
doc/misc
==================================================================
-- Joe Conway
