From: Tom Lane <tgl@sss.pgh.pa.us>
To: Craig James <cjames@emolecules.com>
cc: "pgsql-admin@postgresql.org" <pgsql-admin@postgresql.org>
Subject: Re: WAL size many times data size?
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Comments: In-reply-to Craig James <cjames@emolecules.com>
	message dated "Thu, 10 Nov 2016 06:17:48 -0800"
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Date: Thu, 10 Nov 2016 09:57:57 -0500
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Craig James <cjames@emolecules.com> writes:
> Our streaming replication and WAL archiving keep having trouble because of
> the sheer size of the WAL files. The number of bytes in the WAL files seems
> to be a large multiplier, like 5x or 10x, the amount of data that we load.

My first instinct would be to check how often checkpoints are happening,
and increase the checkpoint control parameters so that they're at least
5 to 15 minutes apart.  A short checkpoint interval leads directly to
WAL bloat because it means more full-page images get inserted into WAL.
(The first change of any given page after a checkpoint requires an FPI.)

			regards, tom lane


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