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Re: Weird 8.2.4 performance

From: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
To: Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>
Cc: Kurt Overberg <kurt(at)hotdogrecords(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Weird 8.2.4 performance
Date: 2007-06-07 23:09:34
Message-ID: 4668902E.4040909@commandprompt.com (view raw or flat)
Thread:
Lists: pgsql-performance
Mark Kirkwood wrote:
> Kurt Overberg wrote:
>> work_mem = 100MB                        # when I ran the original 
>> query, this was set to 1MB, increased on Mark Kirkwood's advice, 
>> seemed to help a bit but not really
>>
> 
> For future reference, be careful with this parameter, as *every* 
> connection will use this much memory for each sort or hash (i.e it's not 
> shared and can be allocated several times by each connection!)...yeah, I 
> know I suggested increasing it to see what effect it would have :-).

This is however a parameter that can be set on the fly for the specific 
query.

Joshua D. Drake


> 
> And I'd agree with Steiner and others, looks like caching effects are 
> the cause of the timing difference between production and the mac!
> 
> Cheers
> 
> Mark
> 
> 
> 
> 
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