From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alexander Okulovich <aokulovich@stiltsoft.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Postgres 15 SELECT query doesn't use index under RLS
Date: Wed, 18 Oct 2023 16:35:50 -0400
Message-ID: <3153246.1697661350@sss.pgh.pa.us> (raw)
In-Reply-To: <dd874d42-ad02-48a6-82db-5666f1ee0ec1@stiltsoft.com>
References: <5c1179bb-240b-4c1c-b4b3-2a24868e44bc@stiltsoft.com>
<1570249.1697228785@sss.pgh.pa.us>
<dd874d42-ad02-48a6-82db-5666f1ee0ec1@stiltsoft.com>
Alexander Okulovich <aokulovich@stiltsoft.com> writes:
> We used the product with the default settings. The requests are simple.
> We didn't change the hardware (actually, we use even more performant
> hardware because of that issue) and DDL. I've checked the request on old
> and new databases. Requests that rely on this index execute more than 10
> times longer. Planner indeed used Index Scan before, but now it doesn't.
> So, from my perspective, the only reason we experience that is database
> logic change.
[ shrug... ] Maybe, but it's still not clear if it's a bug, or an
intentional change, or just a cost estimate that was on the hairy
edge before and your luck ran out.
If you could provide a self-contained test case that performs 10x worse
under v15 than v12, we'd surely take a look at it. But with the
information you've given so far, little is possible beyond speculation.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, aokulovich@stiltsoft.com
Subject: Re: Postgres 15 SELECT query doesn't use index under RLS
In-Reply-To: <3153246.1697661350@sss.pgh.pa.us>
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