Tom Lane wrote:
> Bug #19030 [1] seems to be a fresh report of the problem this patch
> aims to solve.
> [1] https://www.postgresql.org/message-id/flat/19030-944dd78d7ef94c0f%40postgresql.org
>
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.
regards
Marc-Olaf Jaschke