From: marcos sicat <marcos.sicat@atlasifs.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Pavel Stehule <pavel.stehule@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org <pgsql-bugs@lists.postgresql.org>
Subject: Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE
Date: Mon, 28 Apr 2025 21:53:26 +0000
Message-ID: <MW5PR84MB22279A9C3D3990FAC0806679F2812@MW5PR84MB2227.NAMPRD84.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <775999.1745848757@sss.pgh.pa.us>
References: <MW5PR84MB2227AA8FFF0ACD8E02F14F1AF2862@MW5PR84MB2227.NAMPRD84.PROD.OUTLOOK.COM>
<CAFj8pRBygw-a5+LdeWSW=8N091=i2Tgmx=73ORyTv6ksT3Zw5w@mail.gmail.com>
<MW5PR84MB2227BFE47602F2AAED04A0B3F2812@MW5PR84MB2227.NAMPRD84.PROD.OUTLOOK.COM>
<775999.1745848757@sss.pgh.pa.us>
Thanks, Tom.
After you made your recommendation, the result returned much quicker at 2.62 seconds, but v15 is still faster at 1.82 seconds. No modification was made to the function.
[image.png]
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Monday, April 28, 2025 at 9:59 AM
To: marcos sicat <marcos.sicat@atlasifs.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, pgsql-bugs@lists.postgresql.org <pgsql-bugs@lists.postgresql.org>
Subject: Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE
marcos sicat <marcos.sicat@atlasifs.com> writes:
> The function is the same between v15 and v17. Is there a subtle difference in performance for nested subqueries in v17?
Your next step should be to compare the plans for the function's
query. The auto_explain or pg_stat_statements extensions could
be used to check that in-situ, if manually EXPLAINing that query
doesn't yield insight.
regards, tom lane
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Subject: Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE
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