Re: Use fadvise in wal replay

From: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>
To: Jakub Wartak <Jakub(dot)Wartak(at)tomtom(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Kirill Reshke <reshke(at)double(dot)cloud>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Use fadvise in wal replay
Date: 2022-06-21 10:24:01
Message-ID: 1809789D-F3A2-423B-B9B6-3BB34C567594@yandex-team.ru
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> On 21 Jun 2022, at 13:20, Jakub Wartak <Jakub(dot)Wartak(at)tomtom(dot)com> wrote:
>
> Maybe the important question is why would be readahead mechanism be disabled in the first place via /sys | blockdev ?

Because database should know better than OS which data needs to be prefetched and which should not. Big OS readahead affects index scan performance.

Best regards, Andrey Borodin.

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