From: Scott Ribe <scott_ribe@elevated-dev.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: regression in PG 15.1
Date: Mon, 28 Nov 2022 21:55:22 -0700
Message-ID: <B6025887-D73F-4B5B-9925-4DA4B675F7E5@elevated-dev.com> (raw)
In-Reply-To: <311DB0F5-E723-4215-8497-0186A3C25224@elevated-dev.com>
References: <D86D21A2-20CB-4E28-AF0A-8C2C0139DA97@elevated-dev.com>
<543106.1669646690@sss.pgh.pa.us>
<4B29C00C-028D-43AE-98F8-793BFC461CA5@elevated-dev.com>
<554068.1669648550@sss.pgh.pa.us>
<311DB0F5-E723-4215-8497-0186A3C25224@elevated-dev.com>
OK, this is not a regression, but a combination of things:
- in 14, it is searching all partitions, but is fast enough that I never noticed (log_min_duration is 1s)
- in 15, at first try it took 30s for JIT, oops
- with that turned off, performance was still really bad
- statistics were not properly updated after the upgrade to 15
- and a big jump was made in a monotonically increasing serial being searched on
- instead of 142 index scans, 141 returning 0, and 1 returning a few rows, we got 142 seq scans
- problem fixed itself while I was still figuring it all out, because of normal vacuum thresholds
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To: pgsql-admin@postgresql.org
Cc: scott_ribe@elevated-dev.com, tgl@sss.pgh.pa.us, pgsql-admin@lists.postgresql.org
Subject: Re: regression in PG 15.1
In-Reply-To: <B6025887-D73F-4B5B-9925-4DA4B675F7E5@elevated-dev.com>
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