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Re: [GENERAL] Upgrade to dual processor machine?

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: "Henrik Steffen" <steffen(at)city-map(dot)de>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: [GENERAL] Upgrade to dual processor machine?
Date: 2002-11-15 18:55:11
Message-ID: 200211151055.11245.josh@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-performance
Henrik,

> > Well, now it gets more complicated.   You need to determine:
> > A) The median processing time of each of those requests.
> > B) The amount of Sort_mem actually required for each request.
> 
> as I am dealing with postgres for a webserver the median processing
> time of each request has got to be <1 sec. how can i measure
> the amount of sort_mem needed?

Through experimentation, mostly.  SInce you are in a high-volume, small-query 
environment, I would try *lowering* your sort mem to see if that has an 
adverse impact on queries.   A good quick test would be to cut your sort_mem 
in half, and then run an EXPLAIN on the query from which you expect the 
largest result set, and see if the SORT time on the query has been increased.

-- 
-Josh Berkus
 Aglio Database Solutions
 San Francisco


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