Re: Postgres undeterministically uses a bad plan, how to convince it otherwise?

From: cen <cen(dot)is(dot)imba(at)gmail(dot)com>
To: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Cc: pgsql-general <pgsql-general(at)postgresql(dot)org>
Subject: Re: Postgres undeterministically uses a bad plan, how to convince it otherwise?
Date: 2023-02-17 10:30:03
Message-ID: da2deef1-74fd-6745-e85d-37657dc16eb0@gmail.com
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On 16/02/2023 17:07, David G. Johnston wrote:
>
> No, the planner may not cause execution.  While I could imagine
> extending EXPLAIN to somehow retrieve and maybe even try alternative
> plans that have been fully constructed today I'm not holding my breath.
>
> There is little reason for the project to give any real weight to
> "assuming the query to be immutable".  We do want to fix the planner
> to behave better if it is mis-behaving, otherwise you do have access
> to cost parameters, and potentially other planner toggles if you've
> truly run into an intractable problem.
>
> David J.
>
Fair on both points. I didn't know planner toggles existed, I'll play
with that.

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