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Re: Odd behavior with temp usage logging

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Odd behavior with temp usage logging
Date: 2009-01-27 17:33:47
Message-ID: 497F457B.10108@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-performance
Craig Ringer wrote:
> Josh Berkus wrote:
>> Folks,
>>
>> I turned on temp file logging for PostgreSQL to see if I needed to
>> adjust work_mem.  Oddly, it's logging file usage up to 33 times per
>> executed query (and no, the query isn't large enough to need 33 separate
>> sorts).
> 
> Are you sure there's not a sort happening inside a loop? It might help
> if you posted the actual log messages along with the output of `EXPLAIN
> ANALYZE' on your query.

Hmmm, it's possible.  The sort sizes seem very large for the query in 
question, though.  Will have to check when I get back on the system.

That would make a TODO in tempfile logging though ... it would be *far* 
more useful to colect summary stats per query than log each individual sort.

--Josh


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