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From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Mon, 13 May 2024 11:05:40 +0530
Message-ID: <CALj2ACVzL4uU=hxFpSfkqP4HeFCPucbBTEg6HNf_MPTYm52pHg@mail.gmail.com>
Subject: Re: Use WALReadFromBuffers in more places
To: Jingtang Zhang <mrdrivingduck@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
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On Wed, May 8, 2024 at 9:51=E2=80=AFAM Jingtang Zhang <mrdrivingduck@gmail.=
com> wrote:
>
> Hi, Bharath. I've been testing this. It's cool. Is there any way we could
> monitor the hit rate about directly reading from WAL buffers by exporting
> to some views?

Thanks for looking into this. I used purpose-built patches for
verifying the WAL buffers hit ratio, please check
USE-ON-HEAD-Collect-WAL-read-from-file-stats.txt and
USE-ON-PATCH-Collect-WAL-read-from-buffers-and-file-stats.txt at
https://www.postgresql.org/message-id/CALj2ACU9cfAcfVsGwUqXMace_7rfSBJ7%2Bh=
XVJfVV1jnspTDGHQ%40mail.gmail.com.
In the long run, it's better to extend what's proposed in the thread
https://www.postgresql.org/message-id/CALj2ACU_f5_c8F%2BxyNR4HURjG%3DJziiz0=
7wCpQc%3DAqAJUFh7%2B8w%40mail.gmail.com.
I haven't had a chance to dive deep into that thread yet, but a quick
glance over v8 patch tells me that it hasn't yet implemented the idea
of collecting WAL read stats for both walsenders and the backends
reading WAL. If that's done, we can extend it for WAL read from WAL
buffers.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com