The querycache table stores up to 1000 items from the miser'd special
pages (currently Ancientpages, Deadendpages, Lonelypages, Longpages,
Popularpages, Shortpages, Wantedpages) so that display of the special
pages can be done quickly with pre-cached data and nice, navigable
display. (You can change the number of items shown and scroll through,
and wantedpages that are created ought to show as such though i've not
tested this.)
The good: quick response and reasonable display of pages like:
http://de.wikipedia.org/wiki/Spezial:Wantedpages
http://es.wikipedia.org/wiki/Especial:Lonelypages
http://meta.wikipedia.org/wiki/Special:Ancientpages
The bad: it takes a long time to rebuild all the caches for all the
wikis. I've been running it for an hour and it's only up to 'fa' (doing
wikipedia and wiktionary interleaved). For en.wikipedia it's
sufficiently slow that they back up and really slug things down; I ended
up canceling most of the runs on enwiki to keep things running smoothly.
The script to run the rebuilding is recache-all-specials in
/home/wikipedia/bin (it's just a big mass URL hitter.)
So, while reading from the querycache is *great*, we could still use
some improvements on making the original queries more efficient.
Wantedpages and Lonelypages are particularly nasty on superhuge wikis.
-- brion vibber (brion @
pobox.com)