Re: Postgres 15 SELECT query doesn't use index under RLS

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alexander Okulovich <aokulovich(at)stiltsoft(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Postgres 15 SELECT query doesn't use index under RLS
Date: 2023-10-26 14:09:37
Message-ID: 1157086.1698329377@sss.pgh.pa.us
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Alexander Okulovich <aokulovich(at)stiltsoft(dot)com> writes:
> I've attempted to reproduce this on my PC in Docker from the stage
> database dump, but no luck. The first query execution on Postgres 15
> behaves like on the real stage, but subsequent ones use the index.

Can you force it in either direction with "set enable_seqscan = off"
(resp. "set enable_indexscan = off")? If so, how do the estimated
costs compare for the two plan shapes?

> Also,
> they execute much faster. Looks like the hardware and(or) the data
> structure on disk matters.

Maybe your prod installation has a bloated index, and that's driving
up the estimated cost enough to steer the planner away from it.

regards, tom lane

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