Re: WAL file utilization question

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: kadams(at)mxlogic(dot)com
Cc: "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>, pgsql-admin(at)postgresql(dot)org
Subject: Re: WAL file utilization question
Date: 2007-05-16 20:02:57
Message-ID: 6775.1179345777@sss.pgh.pa.us
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Keaton Adams <kadams(at)mxlogic(dot)com> writes:
> Well, no, I'm not that paranoid where I expect checkpoints to be taking
> place so often. I do find it interesting that controlling checkpoint
> frequency is a factor of the number of WAL files available. In order to
> get up to 60 second checkpoints I had to set checkpoint_segments to 25,
> which resulted in the creation of 52 log files in data/pg_xlog. So for
> 120 second checkpoints I will need to have up to 104 log files in
> data/pg_xlog available?

No, it's nonlinear, precisely because of the
checkpoints-increase-the-log-size effect. Given the size of modern
disks, I don't see why a couple Gb of WAL space is a problem anyhow
for a large database.

regards, tom lane

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