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Re: BUG #18627: Regression (15 -> 16) - Join removal not performed when join condition spans multiple tables - Mailing list pgsql-bugs

From David Rowley
Subject Re: BUG #18627: Regression (15 -> 16) - Join removal not performed when join condition spans multiple tables
Date
Msg-id CAApHDvpUiPCefrOL2id3LbF6MC0oiz8pJcDcUw3qZ=aVHjViHQ@mail.gmail.com
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In response to BUG #18627: Regression (15 -> 16) - Join removal not performed when join condition spans multiple tables  (PG Bug reporting form <noreply@postgresql.org>)
Responses Re: BUG #18627: Regression (15 -> 16) - Join removal not performed when join condition spans multiple tables
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On Mon, 23 Sept 2024 at 00:55, PG Bug reporting form
<noreply@postgresql.org> wrote:
> Postgres 15 is able to nicely remove all the joins and gives a nice tidy
> query plan:
> ```
> Seq Scan on origin o  (cost=0.00..16.50 rows=650 width=32)
> ```
>
> Postgres 16 (and 17rc1) on the other hand are giving me this query plan
> instead:
> ```
> Hash Left Join  (cost=24.62..42.84 rows=650 width=32)

Thanks for the report.

It looks like the first bad commit is acc5821e4d (Further fixes in
qual nullingrel adjustment for outer join commutation)

I doubt breaking this was an intended change of the nullable Var work.
Tom can likely confirm.

David

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