Issue status update for http://drupal.org/node/7461 Project: Drupal Version: cvs Component: database system Category: feature requests Priority: normal Assigned to: adrian Reported by: adrian Updated by: adrian -Status: active +Status: closed I am closing this. Look here for a continuation : http://drupal.org/node/19522 adrian Previous comments: ------------------------------------------------------------------------ April 29, 2004 - 23:33 : adrian Attachment: http://drupal.org/files/issues/multi_db_connections.diff (5.23 KB) This patch allows multiple database connections to be used within Drupal. The method of specifying : <?php $db_url = "mysql://user:pass@localhost/dbname"; ?> will still work, it will create the 'default' connection. However, if you need multiple connections .. you can specify : <?php $db_url["default"]      = "mysql://user:pass@localhost/dbname"; $db_url["other_db"]     = "mysql://user:pass@localhost/other_dbname"; $db_url["other_server"] = "mysql://user:pass@my.server.com/dbname"; ?> Within your module you can execute <?php set_active_db("other_db"); //or another named connection ?> to switch the db_api to use that connection. If you do not remember to switch back to default, you might cause interesting errors. so beware. The set_active_db() function defaults it's first parameter to 'default', so you only need to run : <?php set_active_db(); // defaults to 'default' ?> to get back on the right track *Caveats:* If you specify a named connection that doesnt exist, it creates a duplicate of the default. I am not sure if this is the wrong behaviour though, as it is easily fixed , but creating a new pipe is perhaps the desired functionality? I don't know. please comment. Because of the nature of the DB Api , it does not allow you to have both postgres and mysql connections running simultaneously, infact only the first db api include loaded will function. It is beyond the scope of this feature request to rewrite the db api as extensively as is needed to fix this problem. More discussion is needed ------------------------------------------------------------------------ April 30, 2004 - 00:57 : adrian Attachment: http://drupal.org/files/issues/multi_db_connections_0.diff (6.54 KB) added some documentation as per Dries' request ------------------------------------------------------------------------ April 30, 2004 - 07:36 : Dries Committed to HEAD. Thanks Adrian. ------------------------------------------------------------------------ August 25, 2004 - 09:47 : sandeep If I was writing a module that needed to connect to another databases... for example my conf.php might look like this: $db_url["default"] = "mysql://user:pass@localhost/dbname"; $db_url["some_pgsql_db"] = "pgsql://user:pass@localhost/some_pgsql_db"; Within my module I execute set_active_db("some_pgsql_db"); Then I would get the Fatal error "Cannot redeclare..." because now there would be two sets of the db_* functions. One from database.mysql.inc which Drupal will include by default and another from database.pear.inc which my call to set_active_db() will include. ------------------------------------------------------------------------ August 25, 2004 - 10:06 : killes@www.drop.org I think using databases running two different systems is a feature rather than a bug. A feature that I don't think many people will require. There is also no easy way of providing this feature I am afraid. ------------------------------------------------------------------------ August 26, 2004 - 14:40 : sandeep I know of a friend who uses Drupal to manage his entire business process. He has written a custom reporting module that collates data form the Drupal database (MySQL) and his clients database which is in MSSQL. I do agree that not many people will require this feature but its a cool feature to have in a web application platform. I am currently working on a database abstration library based heavily on the Drupal database abstraction library to achieve the above feature. I think it should be fairly easy to implement. The idea is to have a wrapper file that has all the db_* functions. Depending on the current database connection type we can include the appropriate file for that particular database type. Now, the db_* function will check the current database type, for example if it is mysql, then db_connect() will call db_mysql_connect() which is defined in the mysql include file. Similarly, the other databases can be supported with the PEAR db library by defining the db_pear_* functions in the pear include file. When I get enough time to complete my library I will contribute a patch for the Drupal database system. ------------------------------------------------------------------------ September 8, 2004 - 15:55 : adrian Firstly, this patch made it into core early on in the 4.5 work. Secondly, I made a note about not being able to use postgres and mysql in the same application. I think there's even a comment in the source. Thirdly, we are moving away from PEAR in the next release, and mssql is no longer supported by drupal. Fourthly, changing the db api to have db_ functions that redirect to the correct function is probably a good idea, but good luck trying to convince people it's needed as it is such a specific use case. ------------------------------------------------------------------------ November 21, 2004 - 10:52 : Anonymous I think the idea of being able to flick databases is a good one, we are using it within our drupal code :) It seems to have introduced a problem, raised on a seperate report http://drupal.org/node/13115 Thanks, Sil