Re: Removing unneeded self joins

From: Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Zhihong Yu <zyu(at)yugabyte(dot)com>, Ronan Dunklau <ronan(dot)dunklau(at)aiven(dot)io>, Greg Stark <stark(at)mit(dot)edu>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>, Hywel Carver <hywel(at)skillerwhale(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Removing unneeded self joins
Date: 2022-12-16 06:45:30
Message-ID: 36579124-f9d9-a51e-38b3-af3511921c7e@postgrespro.ru
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On 12/6/22 23:46, Andres Freund wrote:
> This doesn't pass the main regression tests due to a plan difference.
> https://cirrus-ci.com/task/5537518245380096
> https://api.cirrus-ci.com/v1/artifact/task/5537518245380096/testrun/build/testrun/regress/regress/regression.diffs
>
> diff -U3 /tmp/cirrus-ci-build/src/test/regress/expected/join.out /tmp/cirrus-ci-build/build/testrun/regress/regress/results/join.out
> --- /tmp/cirrus-ci-build/src/test/regress/expected/join.out 2022-12-05 19:11:52.453920838 +0000
> +++ /tmp/cirrus-ci-build/build/testrun/regress/regress/results/join.out 2022-12-05 19:15:21.864183651 +0000
> @@ -5806,7 +5806,7 @@
> Nested Loop
> Join Filter: (sj_t3.id = sj_t1.id)
> -> Nested Loop
> - Join Filter: (sj_t3.id = sj_t2.id)
> + Join Filter: (sj_t2.id = sj_t3.id)
> -> Nested Loop Semi Join
> -> Nested Loop
> -> HashAggregate
This change in the test behaviour is induced by the a5fc4641
"Avoid making commutatively-duplicate clauses in EquivalenceClasses."
Nothing special, as I see. Attached patch fixes this.

--
Regards
Andrey Lepikhov
Postgres Professional

Attachment Content-Type Size
v39-0001-Remove-self-joins.patch text/x-patch 89.3 KB

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