Re: pg_plan_advice

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Ajay Pal <ajay(dot)pal(dot)k(at)gmail(dot)com>
Cc: Alexandra Wang <alexandra(dot)wang(dot)oss(at)gmail(dot)com>, Richard Guo <guofenglinux(at)gmail(dot)com>, Lukas Fittl <lukas(at)fittl(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jacob Champion <jacob(dot)champion(at)enterprisedb(dot)com>, Dian Fay <di(at)nmfay(dot)com>, Matheus Alcantara <matheusssilv97(at)gmail(dot)com>, Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: pg_plan_advice
Date: 2026-02-12 19:00:22
Message-ID: CA+TgmobRs1a3ctr=_3DozWR4Ftxb0jqrRfZR-hNiGghCcq2AXg@mail.gmail.com
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On Thu, Feb 12, 2026 at 8:08 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Feb 12, 2026 at 6:41 AM Ajay Pal <ajay(dot)pal(dot)k(at)gmail(dot)com> wrote:
> > pg_plan_advice failed to match JOIN_ORDER advice because the genetic
> > algorithm never attempts the specific join path requested.
>
> Seems expected. It is bad if using GEQO results in a crash or if the
> advice cause the expected outcome when the path is considered, but if

sorry, this should have said "doesn't cause"

> the randomness of GEQO causes it not to consider the path the user
> wants, then the user either needs to stop using GEQO, or use
> less-strict plan advice, or just understand that this kind of outcome
> is a possibility.

--
Robert Haas
EDB: http://www.enterprisedb.com

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