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Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE - Mailing list pgsql-bugs

From marcos sicat
Subject Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE
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Msg-id MW5PR84MB22279A9C3D3990FAC0806679F2812@MW5PR84MB2227.NAMPRD84.PROD.OUTLOOK.COM
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In response to Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Postgres 17.4 is much slower than Postgres 15.12 using RECURSIVE
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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.  

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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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