From: Tom Lane <tgl@sss.pgh.pa.us>
To: Scott Ribe <scott_ribe@elevated-dev.com>
cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: measuring WAL creation
In-reply-to: <7058A015-F907-4182-BF9F-9E6904620197@elevated-dev.com>
References: <7058A015-F907-4182-BF9F-9E6904620197@elevated-dev.com>
Comments: In-reply-to Scott Ribe <scott_ribe@elevated-dev.com>
	message dated "Fri, 02 Aug 2024 13:16:06 -0600"
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Date: Fri, 02 Aug 2024 16:29:19 -0400
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Scott Ribe <scott_ribe@elevated-dev.com> writes:
> I'd like to measure both the amount of WAL created by a long series of d=
ata modifications and the compressed size of the generated WAL files.
> I suppose I need to set wal_keep_size high, and pay attention to segment=
 numbers to make sure it was high enough. Then I can look at segments crea=
ted while the commands were running.

> But question: can I simply delete all WAL after a clean shutdown?

As a general rule, never do that manually --- the risk/reward ratio is
unattractive.  A checkpoint will release all safely-releasable WAL.
You can checkpoint via a shutdown if you insist, but a plain
CHECKPOINT command should be enough.

			regards, tom lane