Alex,
I was reading about MySQL's Falcon engine (which appears to have reached an
alpha branch), and was wondering if anyone had tried it with Mediawiki, and for that matter the whole Wikipedia dataset. Curious to know how it behaves, and how much efficiency the compressed storage engine gets...
Falcon isn't suitable for now to run Wikipedia dataset. It doesn't have covering indexes (all reads hit data rows), it doesn't have 'ORDER BY ... LIMIT' optimization, it is hungry for filesorts, etc.
Mediawiki's primary engine is InnoDB, then some sites may attempt to use MyISAM, though that isn't well supported...
For some wikipedias though, BLACKHOLE seems to be the best engine MySQL has produced.
Domas