Horton

Re: Possible regression in PG18 beta1

Sadeq Dousti <msdousti@gmail.com>

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From: Sadeq Dousti <msdousti@gmail.com>
To: Sami Imseih <samimseih@gmail.com>
Cc: Christophe Courtois <christophe.courtois@dalibo.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-05-17T19:00:00Z
Lists: pgsql-hackers

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  1. EXPLAIN: Always use two fractional digits for row counts.

>
> thanks. I don't see regression for a normal table, at least for this test.
>

No, there isn't. I just added them as per your request ;)


In terms of your original test, I tried it out on my Ubuntu machine

and with your test as-is, I see 2.8 seconds on 17.5 and 3.3 seconds

on HEAD if the plan performs a seq scan without parallelism.
>

Which is unexpected, no?


However, the test as you have it is indexing all columns
> on the table. If I just index on the filtered column
>

Yes, I agree. Changing the indexing setup will diminish the difference.
However, given the sub-optimal index, PG18 seems to be slower.

Also, there's a meaningful difference in the plans for TEMP table vs.
UNLOGGED, which is interesting.

Best regards,
Sadeq Dousti