Horton

RE: Using per-transaction memory contexts for storing decoded tuples

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Masahiko Sawada' <sawada.mshk@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-09-17T05:56:23Z
Lists: pgsql-hackers 
Hi,

> We have several reports that logical decoding uses memory much more
> than logical_decoding_work_mem[1][2][3]. For instance in one of the
> reports[1], even though users set logical_decoding_work_mem to
> '256MB', a walsender process was killed by OOM because of using more
> than 4GB memory.

I appreciate your work on logical replication and am interested in the thread.
I've heard this issue from others, and this has been the barrier to using logical
replication. Please let me know if I can help with benchmarking, other
measurements, etc.

Best regards,
Hayato Kuroda
FUJITSU LIMITED

Commits

  1. Reduce memory block size for decoded tuple storage to 8kB.

  2. Generational memory allocator