stores: an array where the keys are DB keys and the values are messages
set in: wfMsg(), Article::editUpdates() both call wfLoadAllMessages()
cleared by: nothing
+
+Watchlist:
+ key: $wgDBname:watchlist:id:$userID
+ ex: wikidb:watchlist:id:4635
+ stores: HTML string
+ cleared by: nothing, expiry time $wgWLCacheTimeout (1 hour)
+ note: emergency optimisation only
+
+IP blocks:
+ key: $wgDBname:ipblocks
+ ex: wikidb:ipblocks
+ stores: array of arrays, for the BlockCache class
+ cleared by: BlockCache:clear()
+
... more to come ...