From: | Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> |
---|---|
To: | KAWAMOTO Masaya <kawamoto(at)sraoss(dot)co(dot)jp> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Proposal: add a debug message about using geqo |
Date: | 2022-05-10 13:19:54 |
Message-ID: | CAExHW5ufGEX9jJ+D1yrCKg3cHPo=Snx7hszOB6TVKNPKeHx5Pw@mail.gmail.com |
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Lists: | pgsql-hackers |
If we add that information to EXPLAIN output, the user won't need
access to server logs.
May be we need it in both the places.
On Tue, May 10, 2022 at 6:35 AM KAWAMOTO Masaya <kawamoto(at)sraoss(dot)co(dot)jp> wrote:
>
> Hi,
>
> During query tuning, users may want to check if GEQO is used or not
> to generate a plan. However, users can not know it by simply counting
> the number of tables that appear in SQL. I know we can know it by
> enabling GEQO_DEBUG flag, but it needs recompiling, so I think it is
> inconvenient.
>
> So, I would like to propose to add a debug level message that shows
> when PostgreSQL use GEQO. That enables users to easily see it by
> just changing log_min_messages.
>
> Use cases are as follows:
> - When investigating about the result of planning, user can determine
> whether the plan is chosen by the standard planning or GEQO.
>
> - When tuning PostgreSQL, user can determine the suitable value of
> geqo_threshold parameter.
>
> Best regards.
>
> --
> KAWAMOTO Masaya <kawamoto(at)sraoss(dot)co(dot)jp>
> SRA OSS, Inc. Japan
--
Best Wishes,
Ashutosh Bapat
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