QUOTE(Tarc @ Mon 14th May 2012, 1:42pm)
Looks like they're adding a field to the en.wiki db; every entry in there has to be touched, and it is taking longer than initially anticipated.
Yes, the new field is a hash value for every revision of every page, which will help check whether a series of edits actually made any change. I don't see any evidence that such a check could ever happen often enough that an ordinary string comparison of the page text is insufficiently fast.
In the mean time a whole lot of toolserver scripts, queries, and bots are broken or buggy, including some that are very important for behind the scenes maintenance.