| From: | <Holger(dot)Friedrich-Fa-Trivadis(at)it(dot)nrw(dot)de> |
|---|---|
| To: | <pgsql-general(at)postgresql(dot)org>, <laurenz(dot)albe(at)wien(dot)gv(dot)at>, <andreas(at)a-kretschmer(dot)de> |
| Subject: | Re: How to craft a query that uses memory? |
| Date: | 2015-06-19 13:21:29 |
| Message-ID: | C5DBACC6DCC7604C9E4875FD9C7968B11A148D160E@ITXS01EVS.service.it.nrw.de |
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| Lists: | pgsql-general |
Albe Laurenz wrote on Friday, June 19, 2015 12:56 PM:
> Holger Friedrich wrote:
> > So how do I craft a query that actually does use lots of memory?
> You increase the parameter "work_mem".
> You can do that globally in postgresql.conf or with SET for one session or with SET LOCAL for one transaction.
Thank you to both Albe Laurenz and Andreas Kretschmer, who both gave the same advice. It was spot-on: my query actually seems to be good for a performance study, setting work_mem to various values causes the query planner to either sort in memory or on disk, and of course this has some impact on performance.
(Sorry for erroneously asking for suggesting a "better" query, rather than for tuning my configuration, which turned out to be the sensible thing to do...)
Best regards,
Holger Friedrich
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