From: Tom Lane <tgl@sss.pgh.pa.us>
To: github@jurr.org
cc: pgsql-docs@lists.postgresql.org
Subject: Re: Chapter 14.1.1, small typo on costs?
In-reply-to: <160362404830.24751.12549386489720350845@wrigleys.postgresql.org>
References: <160362404830.24751.12549386489720350845@wrigleys.postgresql.org>
Comments: In-reply-to PG Doc comments form <noreply@postgresql.org>
	message dated "Sun, 25 Oct 2020 11:07:28 -0000"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <572472.1603653373.1@sss.pgh.pa.us>
Date: Sun, 25 Oct 2020 15:16:13 -0400
Message-ID: <572473.1603653373@sss.pgh.pa.us>
Precedence: bulk

PG Doc comments form <noreply@postgresql.org> writes:
> I am reading 14.1.1 and at the very end (just before 14.1.2) I see:

> "which shows that the planner thinks that sorting onek by index-scanning is
> about 12% more expensive than sequential-scan-and-sort."

> I feel that 12% is incorrect, but I'm not quite sure. The costs are 268.19
> and 292.65, and that's about 9% more expensive?

No, the comparison this has in mind is 224.79 (the indexscan on onek
in the last plan) versus 200.33 (the sort on onek in the previous plan).
So 12% is about right.

			regards, tom lane