Last modified: 2011-11-29 22:12:28 UTC
It might be useful to have a special page or script which listed the past categories of a given page. A lot of pages on my watchlist are things like [[stain]], which have a lot of opinionated editors but very few experts. Ideally, this page would list all of the categories that the page has ever been in, sorted by how many edits the page remained in that category. (So, for example, if [[Stain]] was in [[Category:Laundry]] for 20 edits, that's a sign that it's a more likely category than [[Category:Star Wars Villains]] which it might have been in for 1 edit.). I guess this is kind of a specialized request.
We don't store information on old category relationships anywhere at present; it's all "current state". We'd need to introduce some sort of category link versioning system to be able to support this.
This is possible, but not something we're looking to do for the foreseeable future.
I guess the best way to do this, barring any change to the db schema, is to analyze the full XML dumps.