From: Tom Lane <tgl@sss.pgh.pa.us>
To: Craig A. James <cjames@modgraph-usa.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Poor performance o
Date: Tue, 21 Mar 2006 23:31:43 -0500
Message-ID: <10012.1143001903@sss.pgh.pa.us> (raw)
In-Reply-To: <4420A290.2050908@modgraph-usa.com>
References: <43F38867.6010701@gpdnet.co.uk>
<19510.1140036968@sss.pgh.pa.us>
<19779.1140038874@sss.pgh.pa.us>
<43F39E53.1020009@gpdnet.co.uk>
<20781.1140046109@sss.pgh.pa.us>
<19570.1142971720@sss.pgh.pa.us>
<442080D1.5090803@modgraph-usa.com>
<6629.1142983995@sss.pgh.pa.us>
<4420A290.2050908@modgraph-usa.com>
"Craig A. James" <cjames@modgraph-usa.com> writes:
> Tom Lane wrote:
>> Given the sizes of the tables involved, you'd likely have to boost up
>> work_mem before the planner would consider a hash join. What nondefault
>> configuration settings do you have, anyway?
> shared_buffers = 20000
> work_mem = 32768
> effective_cache_size = 300000
So for a 6M-row table, 32M work_mem would allow ... um ... 5 bytes per
row. It's not happening :-(
Try boosting work_mem by a factor of 100 and seeing whether a hash-based
join actually wins or not. If so, we can discuss where the sane setting
really falls, if not there's no point.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, cjames@modgraph-usa.com
Subject: Re: Poor performance o
In-Reply-To: <10012.1143001903@sss.pgh.pa.us>
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