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From: Pavel Luzanov <[email protected]>
To: Melanie Plageman <[email protected]>
To: Peter Geoghegan <[email protected]>
Cc: pgsql-generallists.postgresql.org <[email protected]>
Cc: Heikki Linnakangas <[email protected]>
Subject: Re: PG17 optimizations to vacuum
Date: Mon, 2 Sep 2024 23:35:04 +0300
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAAKRu_YF9UeFnfsgDiFybAss2YQtmEHU+xjngqwmwwyQjCDvxQ@mail.gmail.com>
References: <[email protected]>
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	<CAAKRu_YF9UeFnfsgDiFybAss2YQtmEHU+xjngqwmwwyQjCDvxQ@mail.gmail.com>

On 02.09.2024 22:23, Melanie Plageman wrote:
> For some reason I stopped being able to reproduce Pavel's case.

I repeated the test on another computer, but compared master with v15.
The results are the same. The test can be simplified as follows:

CREATE TABLE t(id integer) WITH (autovacuum_enabled = off);
INSERT INTO t SELECT gen.id FROM generate_series(1,3_500_000) gen(id);
CREATE INDEX t_id ON t(id);
VACUUM FREEZE t;
UPDATE t SET id = id + 1;
VACUUM FREEZE VERBOSE t;

My results (only line with WAL info from the last VACUUM command).

master:
WAL usage: 119583 records, 37231 full page images, 272631468 bytes

v15:
WAL usage: 96565 records, 47647 full page images, 217144602 bytes


If it helps, without creating index on id column, the numbers will be
much closer:

master:
WAL usage: 78502 records, 22090 full page images, 196215494 bytes

v15:
WAL usage: 77437 records, 30872 full page images, 152080268 bytes

-- 
Pavel Luzanov
Postgres Professional:https://postgrespro.com


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