Is there any way to tune cache_moderators()?

[Clockwork]

I've a pretty big userbase (2 million registered users) and much moderators.

Because of this the left join query in cache_modertors takes too long and locks the usertable.

Is there any way to tune this function/query? Perhaps by disabling some features?

[Homeworld'sa]

Are you on a dedicated server or a VPS? You could try posting a server optimisation request.

[Clockwork]

The board runs on 5 dedicated servers. Imo that left join is the problem, not the servers.

Can someone explain me for what is that function being used?

[kmike]

It's used to show forum moderators on the forum display page, and in numerous other places to fetch moderator permission data. You are probably right that the LEFT JOIN isn't needed in those other places - the LEFT JOIN is there just to fetch the mods' usernames.
But you can't really tune it without editing the sources.
To eliminate locking, you can convert the user table (and the moderator table, if it's big) to InnoDB.

[Clockwork]

let's say I would remove the left join from the query, what would be broken? Only the modertor list at the forum display page?

[kmike]

I think so. Also the moderator column in the forum list would be affected, if you have it turned on.

[Removed-836727]

Wouldn't it be possible to put this result into the new vB_Cache System???

YOu don't need to grab everytime for the moderators.
I think it would be enought to create the cached element and to delete it, when a admin adds/modifies/deletes the moderats (or of you cache everything, also when a user is edited, for example change username)

[Clockwork]

New cache system? Is that possible in 3.8?

[Removed-836727]

Ups.
Sorry, haven't seen that this is in the 3.8 section