> -----Original Message-----
> From: Anne Rosset [mailto:arosset@collab.net]
> Sent: Monday, May 06, 2013 1:01 PM
> To: Igor Neyman; ktm@rice.edu
> Cc: pgsql-performance@postgresql.org
> Subject: RE: [PERFORM] Deterioration in performance when query executed
> in multi threads
>
> Hi Igor,
> The explain analyze is from when there was no load.
>
> Artifact table: 251831 rows
> Field_value table: 77378 rows
> Mntr_subscription: 929071 rows
> Relationship: 270478 row
> Folder: 280356 rows
> Item: 716465 rows
> Sfuser: 5733 rows
> Project: 1817 rows
>
> 8CPUs
> RAM: 8GB
>
> Postgres version: 9.0.13
>
> And no we haven't switched or tested yet with pgbouncer. We would
> like to do a bit more analysis before trying this.
>
> Thanks for your help,
> Anne
>
>
Anne,
Just as a quick test, try in the psql session/connection locally change enable_nestloop setting and run your query:
set enable_nestloop = off;
explain analyze <your_query>;
just to see if different execution plan will be better and optimizer needs to be "convinced" to use this different
plan.
Please post what you get with the modified setting.
Also, what is the setting for effective_cache_size in postgresql.conf?
Regards,
Igor Neyman