Re: explain analyze reports that my queries are fast but they run very slowly

Thanks!

http://explain.depesz.com/s/yfs

Looks like we're running a load of about 6. The machines have two physical
cores hyperthreaded to 32 cores.

Interesting - the data is stored on nfs on a netapp. We don't seem to have
a ton of nfs traffic.

Also we've got shared memory set to 48 gigs which is comfortably less than
the 146 gigs in the machine.

On Thu, Dec 27, 2012 at 12:21 PM, François Beausoleil
<francois(at)teksol(dot)info>wrote:

>
> Le 2012-12-27 à 12:10, Nikolas Everett a écrit :
>
> > We just upgraded from 8.3 to 9.1 and we're seeing some performance
> problems. When we EXPLAIN ANALYZE our queries the explain result claim
> that the queries are reasonably fast but the wall clock time is way way
> longer. Does anyone know why this might happen?
> >
> > Like so:
> > db=>\timing
> > db=>EXPLAIN ANALYZE SELECT max(id) FROM foo WHERE blah_id = 1209123;
> >
> > The plan is sensible. The estimates are sensible. The actual DB time
> reads like it is very sensible. But the wall clock time is like 11 seconds
> and the \timing report confirms it.
> >
> > Any ideas?
>
> Could you post the actual plans? On both versions? That would help a lot.
>
> Also, http://explain.depesz.com/ helps readability.
>
> Bye,
> François
>
>