Re: BUG #6275: Horrible performance regression

On Sun, Oct 30, 2011 at 10:30 PM, Finlay Thompson
<finlay@dragonfly.co.nz> wrote:
> Hi Tom
>
> Sorry for the delay.
>
> The version of postgis didn't change, and when I rolled back to
> postgresql 8.4.9 the expected performance returned. I am very confident
> the regression was caused by the 8.4.9 upgrade.
>
> Any suggestions on how to diagnose a long run script like this ? I can
> easily turn on more logging, in both cases and compare ? Can I log the
> query plans ?

The easiest thing to do is probably EXPLAIN ANALYZE each query and
post the output to this thread.

If you can't do that for some reason, there's always auto_explain, but
that has some overhead and is a bit more work to set up.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company