Message-ID: <1662df4d-f0d4-456b-bc0e-660f01f3a122@iki.fi>
Date: Tue, 3 Sep 2024 13:04:43 +0300
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Subject: Re: PG17 optimizations to vacuum
To: Pavel Luzanov <p.luzanov@postgrespro.ru>, Peter Geoghegan <pg@bowt.ie>
Cc: Melanie Plageman <melanieplageman@gmail.com>,
 "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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From: Heikki Linnakangas <hlinnaka@iki.fi>
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On 03/09/2024 10:34, Pavel Luzanov wrote:
> On 03.09.2024 00:11, Heikki Linnakangas wrote:
>> Pavel, did you test v17 with checksums enabled and v16 with checksums 
>> disabled, by any chance?
> 
> Exactly, You are right!
> 
> My v16 cluster comes from the default Ubuntu distribution.
> I forgot that checksums disabled by default.
> But when I initialize the master cluster, I automatically set -k option.
> 
> More accurate results for the test:
> 
> CREATE TABLE t(id integer) WITH (autovacuum_enabled = off);
> INSERT INTO t SELECT gen.id FROM generate_series(1,3_500_000) gen(id);
> VACUUM FREEZE t;
> UPDATE t SET id = id + 1;
> VACUUM FREEZE VERBOSE t;
> 
> checksums disabled
> v16.4	WAL usage: 77437 records, 20832 full page images, 110654467 bytes
> master	WAL usage: 61949 records, 20581 full page images, 92549229 bytes
> 
> checksums enabled
> v16.4	WAL usage: 92848 records, 20985 full page images, 194863720 bytes
> master	WAL usage: 76520 records, 20358 full page images, 181867154 bytes

That's more like it :-)

> This a great optimization!
> 
> Peter, Melanie, Heikki, 
> Thank you very much for your help and time spent!
> Sorry for the noise before the release of PG17.

Thanks for the testing!

-- 
Heikki Linnakangas
Neon (https://neon.tech)