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177 lines
7.3 KiB
Plaintext
177 lines
7.3 KiB
Plaintext
/*
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* dblink
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*
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* Functions returning results from a remote database
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*
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* Joe Conway <mail@joeconway.com>
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* And contributors:
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* Darko Prenosil <Darko.Prenosil@finteh.hr>
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* Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
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*
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* Copyright (c) 2001-2003, PostgreSQL Global Development Group
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* ALL RIGHTS RESERVED;
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose, without fee, and without a written agreement
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* is hereby granted, provided that the above copyright notice and this
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* paragraph and the following two paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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*/
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Version 0.6 (14 June, 2003):
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Completely removed previously deprecated functions. Added ability
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to create "named" persistent connections in addition to the single global
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"unnamed" persistent connection.
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Tested under Linux (Red Hat 9) and PostgreSQL 7.4devel.
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Release Notes:
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Version 0.6
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- functions deprecated in 0.5 have been removed
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- added ability to create "named" persistent connections
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Version 0.5
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- dblink now supports use directly as a table function; this is the new
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preferred usage going forward
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- Use of dblink_tok is now deprecated; original form of dblink is also
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deprecated. They _will_ be removed in the next version.
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- dblink_last_oid is also deprecated; use dblink_exec() which returns
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the command status as a single row, single column result.
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- Original dblink, dblink_tok, and dblink_last_oid are commented out in
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dblink.sql; remove the comments to use the deprecated functions.
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- dblink_strtok() and dblink_replace() functions were removed. Use
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split() and replace() respectively (new backend functions in
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PostgreSQL 7.3) instead.
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- New functions: dblink_exec() for non-SELECT queries; dblink_connect()
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opens connection that persists for duration of a backend;
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dblink_disconnect() closes a persistent connection; dblink_open()
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opens a cursor; dblink_fetch() fetches results from an open cursor.
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dblink_close() closes a cursor.
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- New test suite: dblink_check.sh, dblink.test.sql,
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dblink.test.expected.out. Execute dblink_check.sh from the same
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directory as the other two files. Output is dblink.test.out and
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dblink.test.diff. Note that dblink.test.sql is a good source
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of example usage.
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Version 0.4
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- removed cursor wrap around input sql to allow for remote
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execution of INSERT/UPDATE/DELETE
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- dblink now returns a resource id instead of a real pointer
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- added several utility functions -- see below
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Version 0.3
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- fixed dblink invalid pointer causing corrupt elog message
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- fixed dblink_tok improper handling of null results
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- fixed examples in README.dblink
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Version 0.2
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- initial release
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Installation:
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Place these files in a directory called 'dblink' under 'contrib' in the PostgreSQL source tree. Then run:
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make
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make install
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You can use dblink.sql to create the functions in your database of choice, e.g.
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psql -U postgres template1 < dblink.sql
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installs following functions into database template1:
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connection
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------------
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dblink_connect(text) RETURNS text
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- opens an unnamed connection that will persist for duration of
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current backend or until it is disconnected
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dblink_connect(text,text) RETURNS text
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- opens a named connection that will persist for duration of current
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backend or until it is disconnected
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dblink_disconnect() RETURNS text
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- disconnects the unnamed persistent connection
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dblink_disconnect(text) RETURNS text
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- disconnects a named persistent connection
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cursor
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------------
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dblink_open(text,text) RETURNS text
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- opens a cursor using unnamed connection already opened with
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dblink_connect() that will persist for duration of current backend
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or until it is closed
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dblink_open(text,text,text) RETURNS text
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- opens a cursor using a named connection already opened with
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dblink_connect() that will persist for duration of current backend
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or until it is closed
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dblink_fetch(text, int) RETURNS setof record
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- fetches data from an already opened cursor on the unnamed connection
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dblink_fetch(text, text, int) RETURNS setof record
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- fetches data from an already opened cursor on a named connection
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dblink_close(text) RETURNS text
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- closes a cursor on the unnamed connection
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dblink_close(text,text) RETURNS text
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- closes a cursor on a named connection
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query
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------------
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dblink(text,text) RETURNS setof record
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- returns a set of results from remote SELECT query; the first argument
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is either a connection string, or the name of an already opened
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persistant connection
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dblink(text) RETURNS setof record
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- returns a set of results from remote SELECT query, using the unnamed
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connection already opened with dblink_connect()
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execute
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------------
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dblink_exec(text, text) RETURNS text
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- executes an INSERT/UPDATE/DELETE query remotely; the first argument
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is either a connection string, or the name of an already opened
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persistant connection
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dblink_exec(text) RETURNS text
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- executes an INSERT/UPDATE/DELETE query remotely, using connection
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already opened with dblink_connect()
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misc
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------------
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dblink_current_query() RETURNS text
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- returns the current query string
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dblink_get_pkey(text) RETURNS setof text
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- returns the field names of a relation's primary key fields
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dblink_build_sql_insert(text,int2vector,int2,_text,_text) RETURNS text
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- builds an insert statement using a local tuple, replacing the
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selection key field values with alternate supplied values
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dblink_build_sql_delete(text,int2vector,int2,_text) RETURNS text
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- builds a delete statement using supplied values for selection
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key field values
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dblink_build_sql_update(text,int2vector,int2,_text,_text) RETURNS text
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- builds an update statement using a local tuple, replacing the
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selection key field values with alternate supplied values
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Documentation:
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Note: Parameters representing relation names must include double
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quotes if the names are mixed-case or contain special characters. They
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must also be appropriately qualified with schema name if applicable.
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See the following files:
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doc/connection
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doc/cursor
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doc/query
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doc/execute
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doc/misc
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doc/deprecated
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==================================================================
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-- Joe Conway
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