From: Tom Lane <tgl@sss.pgh.pa.us>
To: Stephen Frost <sfrost@snowman.net>
cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
        Alvaro Herrera <alvherre@alvh.no-ip.org>,
        Laurenz Albe <laurenz.albe@cybertec.at>,
        "Bossart,
    Nathan" <bossartn@amazon.com>,
        Michael Paquier <michael@paquier.xyz>,
        Bernd Helmle <mailings@oopsware.de>,
        "tsunakawa.takay@fujitsu.com" <tsunakawa.takay@fujitsu.com>,
        "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Change default of checkpoint_completion_target
In-reply-to: <20210119191450.GO27507@tamriel.snowman.net>
References: <20201210171602.GP16415@tamriel.snowman.net>
 <20201210172126.GA25979@alvherre.pgsql>
 <20201210172255.GQ16415@tamriel.snowman.net>
 <20210113221038.GG27507@tamriel.snowman.net>
 <ba8bb5e9-8c43-11b6-eb99-ae794cd37665@enterprisedb.com>
 <20210119191450.GO27507@tamriel.snowman.net>
Comments: In-reply-to Stephen Frost <sfrost@snowman.net>
	message dated "Tue, 19 Jan 2021 14:14:50 -0500"
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Date: Tue, 19 Jan 2021 14:30:46 -0500
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Stephen Frost <sfrost@snowman.net> writes:
> Any further comments or thoughts on this one?

This:

+        total time between checkpoints. The default is 0.9, which spreads the
+        checkpoint across the entire checkpoint timeout period of time,

is confusing because 0.9 is obviously not 1.0; people will wonder
whether the scale is something strange or the text is just wrong.
They will also wonder why not use 1.0 instead.  So perhaps more like

	... The default is 0.9, which spreads the checkpoint across almost
	all the available interval, providing fairly consistent I/O load
	while also leaving some slop for checkpoint completion overhead.

The other chunk of text seems accurate, but there's no reason to let
this one be misleading.

			regards, tom lane