I had a read of Percona’s blog regarding multiple key caches.
I currently have one key cache and run an online forum (not dissimilar to this one).
The four most active tables would be posts, threads, private messages, members so they are probably good contenders for their own key caches.
Members come and go, so the actual ‘active’ members would be a percentage of the registered members. Same goes for posts, there are many, but only recent ones have the most activity.
As actual “active” data is much less than total data, should I base each key cache on “active” data or the total?
If other table data becomes more “active”, does the lower use key cache data get replaced automatically with the most active data?
Has anyone had real world experience with multiple key caches, especially with forums?