Re: PG 15 (and to a smaller degree 14) regression due to ExprEvalStep size - Mailing list pgsql-hackers

From Andres Freund
Subject Re: PG 15 (and to a smaller degree 14) regression due to ExprEvalStep size
Date
Msg-id 20220617052228.mjwns6ugspihamsc@alap3.anarazel.de
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In response to Re: PG 15 (and to a smaller degree 14) regression due to ExprEvalStep size  (David Rowley <dgrowleyml@gmail.com>)
Responses Re: PG 15 (and to a smaller degree 14) regression due to ExprEvalStep size
List pgsql-hackers
Hi,

On 2022-06-17 16:53:31 +1200, David Rowley wrote:
> On Fri, 17 Jun 2022 at 15:33, Peter Geoghegan <pg@bowt.ie> wrote:
> > Have you tried this with the insert benchmark [1]?
> 
> I was mostly focusing on the performance of the hashed saop feature
> after having removed the additional fields that pushed ExprEvalStep
> over 64 bytes in 14.
> 
> I agree it would be good to do further benchmarking to see if there's
> anything else that's snuck into 15 that's slowed that benchmark down,
> but we can likely work on that after we get the ExprEvalStep size back
> to 64 bytes again.

I did reproduce a regression between 14 and 15, using both pgbench -Mprepared
-S (scale 1) and TPC-H Q01 (scale 5). Between 7-10% - not good, particularly
that that's not been found so far. Fixing the json size issue gets that down
to ~2%. Not sure what that's caused by yet.

Greetings,

Andres Freund

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