Last modified: 2010-05-15 15:32:54 UTC
For en wikipedia and all non-big wikis at Wikimedia I've done "alter table cur drop index cur_namespace". This index was too often being used for queries like Parser:replaceLinkHolders, the 500 article allpages subpages and other things where namespace_title should be used. The rest of the wikis will be changed during off peak read only time. If not already done, I recommend that this index be removed from all MediaWiki installations by the installer. May already have been done - I recall past discussion of this.
As far as I can tell, a new 1.4beta installation does not include this index, but an upgrade from 1.3x does not remove it automatically yet.
No longer an issue, since cur is dead. ;)