Unofficial Christ's Hospital Forum

jtaylor wrote:Well, I spotted an issue with the phpbb_sessions table this evening.

It had 55Meg of "overhead".
Tried an overhead, tried a repair - mysqladmin wouldn't let me do it, "The handler for the table doesn't support optimize" and same message for repair.

Copied the table, renamed old one, and overhead has gone.

Any techies out there know the implications of this??

J

It's nothing to do with Saddam Hussein. I know that much.

My experience of phpBB is limited, to say the least. But I have Google, a little guesswork, and a deceptive air of authority. This may not be the right answer, but it might give you some ideas.

You're probably using an in-memory table for sessions rather than one stored on disk. That improves performance, but session data is lost when MySQL is restarted. Depending on how your hosting provider does accounting, it may also prevent session data from counting against your storage allowance.

Session data is information about who's logged in at any one time. If it's lost, it just means that people have to log in again. Since people can log in and out many times a day, it changes a lot more often than the rest of the database, but doesn't need to be preserved long-term.

As you've discovered, you can't optimize a table that's stored in memory. I expect the idea is you don't need to. It's possible you've found a bug in MySQL.

Restart the MySQL server, drop and recreate the table, or upgrade MySQL.

It might be the reported memory use is wrong, though, and this 'overhead' is a phantom. See, for example, bug #18610. If that's the problem, you needn't do anything, unless you care about accurate statistics.

See - I was right! ( I think!)

I'm even more lost now !

Incidently, Dave, I suggest you leave Amy's thrust out of this.

DIVERT ALERT !

Have you posted on the phpBB forum for site owners Julian? They sometimes come up with clever answers to knotty questions

well im going to try and thrust in the right sense now! That post will have made sense to all computer understanderers!

blondie95 wrote:well im going to try and thrust in the right sense now! That post will have made sense to all computer understanderers!

I thought I was a computer understanderer until I read that bit about the Iraqi.

Scone Lover wrote:Have you posted on the phpBB forum for site owners Julian? They sometimes come up with clever answers to knotty questions

Haven't posted on there, but do use it quite a bit for answers/fixes.

The more I've read, the more it's clear that our little forum is tiny compared to some, both in storage space and in number of users.
Hence, most of the suggested speed improvements just aren't relevent for such a small database.
I'm more thinking that the shared hosting is the issue, and that our SQL server is probably getting hit hard on some other sites, which is affecting ours.

One more thing I'm going to try this evening is to move the database over to the second SQL database we have with the hosting - this may be on a different server, which isn't getting hit so hard.

This SHOULD be quite quick (famous last words!)

Hence, forum will be disabled for a while this evening.

J

It must have worked, then !