Last modified: 2012-08-12 19:29:11 UTC
Each wiki of a wiki farm has it own interwiki table with all the prefix and the options for interwikis. In my opinion it is better to set up one shared interwiki table for all wikis of a wiki farm. But that needs support inside MediaWiki: MediaWiki needs a new config global (maybe call it $wgInterwikiCentralDB) and than you have to pass this global to all wfGetDB when accessing the interwiki table. At least remove $wgLocalInterwiki from that list. Having this global allow also to set up a different database for secure server. Than all interwiki links in 'Other languages' on that wiki farm are pointing to a secure server and there is no need for javascripts hacks on each wiki. Thanks.
For wiki farm that does not have multiple clusters, the interwiki table can be added to $wgSharedTables.
For 3rd-party installs, you can easily use $wgSharedTables like comment 1 points out. For WMF usage, we've got bug 11423. WORKSFORME or DUPLICATE?
bug 11423 is over storing the interwiki from pages in a central database, not for the interwiki prefixes of the wiki. (interwiki table vs. langlinks table).
per comment 1