Re: Performance degradation

zabutimaxim_at_gmail.com wrote:
> Hi pobox,
>
> Actually I do it like your second option. But I think I don't
> need solution, I already found it by adding index, there is no
> more degradation (at least not after 2-3 hours :) )
> All I want is a good explanation for "why the index solved
> degradation?"
> I mean same SQL on same table should take same time right
> after restart and after 2-3 hours of work. Or I miss something?
>
>
> Thanks,
> Maxim.
>

Not knowing your application (what does it do besides the select), and also not having any information what it was the session doing the selects were waiting for, it's quite hard to tell.

If you had done an extended trace on the sessions with event 10046, level 12, or a statspack 5 minutes worth while the database appears fast and another while the database appears slow, you might get some answers.

But since your CPU on both the webserver and the database sit idle around, I'd suspect either general IO or excessive Swapping to be the root cause. The latter might be caused by an oversized Buffercache, but thats just a wild shot in the dark.

Cheers
Holger Received on Thu Apr 14 2005 - 06:35:06 CDT