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unlike template0 and template1 does not have any special status in terms of backend functionality. However, all external utilities such as createuser and createdb now connect to "postgres" instead of template1, and the documentation is changed to encourage people to use "postgres" instead of template1 as a play area. This should fix some longstanding gotchas involving unexpected propagation of database objects by createdb (when you used template1 without understanding the implications), as well as ameliorating the problem that CREATE DATABASE is unhappy if anyone else is connected to template1. Patch by Dave Page, minor editing by Tom Lane. All per recent pghackers discussions. |
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dblink.c | ||
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dblink.sql.in | ||
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README.dblink |
/* * 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