Trouble adding column to database table programmatically due to a shared wiki database - MediaWiki-l

3 Jul 2014

Hello,

I am attempting to add a column to the *interwiki *table programmatically
in a MediaWiki extension, using a PHP function registered with the
LoadExtensionSchemaUpdates hook. I've been trying to follow the information
from this link
<http://www.mediawiki.org/wiki/Manual:Hooks/LoadExtensionSchemaUpdates>.
However, our setup appears to be causing a complication. I'm sorry if the
following email is long; I just want to make sure I've described our setup
in sufficient detail.

We run a wiki farm with multiple wikis which share the interwiki table.
However, unlike the process described in this link
<http://www.mediawiki.org/wiki/Manual:Shared_database>, we don't have one
wiki set as the 'main' wiki whose interwiki table is shared with all of the
others; rather, we have created an independent database called
*SHARED_WIKI_TABLES
*which contains at the moment only one table, the interwiki table. Then in
our global LocalSettings.php file, we have the following lines:

*$wgSharedDB = "SHARED_WIKI_TABLES";*
*$wgSharedPrefix = false;*
*$wgSharedTables = array( 'interwiki' );*

Consequently, each wiki has its own interwiki table, but there is also a
shared database interwiki table which belongs to no particular wiki.
Whenever we make database reads, it always reads from the shared interwiki
table. In effect, the shared interwiki table overrides the individual
wikis' interwiki tables. So there's never been a problem before.

Recently I have written an extension which calls the
LoadExtensionSchemaUpdates hook to add some columns to the interwiki table.
However, when I run *php update.php --doshared* on one of our wikis
(--doshared to ensure that shared tables are also updated), what ends up
happening is that the wiki's particular interwiki table is updated, but the
shared wiki table in SHARED_WIKI_TABLES is not updated. Then when we try to
do database reads, they still read from the shared interwiki table, which
was never updated, and we have problems. Furthermore, because
SHARED_WIKI_TABLES is not a database, we can't run update.php on it
directly to update its tables.

So my question is, will we have to change our set-up to account for this,
where we'll have to pick one of our wikis to be the 'main' wiki whose
interwiki table is shared with all of the others? Or is there a way around
this problem?

Thanks!

--
Jason Ji
jason.y.ji(a)gmail.com