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From: Gregory Stark <stark@enterprisedb.com>
To: Joshua D. Drake <jd@commandprompt.com>
Cc: Jonathan Ellis <jonathan@utahpython.org>
Cc: smiley2211 <smiley2211@yahoo.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: How to ENABLE SQL capturing???
Date: Mon, 13 Aug 2007 17:02:41 +0100
Message-ID: <87vebjqv6m.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <46C07BFA.8000500@commandprompt.com>
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	<12096180.post@talk.nabble.com>
	<Pine.LNX.4.64.0708101309230.1940@discord.home.frostconsultingllc.com>
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	<46BCDDAA.3060703@commandprompt.com>
	<e06563880708130804i5f9277f1pe62e85c6c1e69df@mail.gmail.com>
	<46C07BFA.8000500@commandprompt.com>

"Joshua D. Drake" <jd@commandprompt.com> writes:

> If I recall correctly, it is because syslog is blocking.

Are you sure it isn't just that syslog fsyncs its log files after every log
message? I don't think the individual syslogs are synchronous but if syslog
falls behind the buffer will fill and throttle the sender.

If your Postgres data is on the same device as the syslogs those fsyncs will
probably cause a big slowdown directly on Postgres's I/O as well.

You can turn off the fsyncs in syslog by putting a - before the filename.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com



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