Re: Improve hash join's handling of tuples with null join keys

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Marc-Olaf Jaschke <moj(at)dshare(dot)de>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Improve hash join's handling of tuples with null join keys
Date: 2025-08-24 19:18:33
Message-ID: 470075.1756063113@sss.pgh.pa.us
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Marc-Olaf Jaschke <moj(at)dshare(dot)de> writes:
> I can confirm that the patch fixes the issue (Bug #19030). The memory usage remains within the expected range of work_mem.
> This also applies to parallel hash joins.
> The query also runs significantly faster.
> I also tested cases with multiple left joins.
> I have only observed this problem when there are many null values in the join column.

Thanks for testing!

regards, tom lane

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