Horton

Re: Performance degradation on concurrent COPY into a single relation in PG16.

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-07-10T15:34:45Z
Lists: pgsql-hackers 
Hi,

On 2023-07-03 11:55:13 +0900, Masahiko Sawada wrote:
> While testing PG16, I observed that in PG16 there is a big performance
> degradation in concurrent COPY into a single relation with 2 - 16
> clients in my environment. I've attached a test script that measures
> the execution time of COPYing 5GB data in total to the single relation
> while changing the number of concurrent insertions, in PG16 and PG15.
> Here are the results on my environment (EC2 instance, RHEL 8.6, 128
> vCPUs, 512GB RAM):

Gah, RHEL with its frankenkernels, the bane of my existance.

FWIW, I had extensively tested this with XFS, just with a newer kernel. Have
you tested this on RHEL9 as well by any chance?

Greetings,

Andres Freund

Commits

  1. Avoid edge case in pg_visibility test with small shared_buffers

  2. Fix bulk table extension when copying into multiple partitions

  3. hio: Take number of prior relation extensions into account

  4. Fix performance regression in pg_strtointNN_safe functions

  5. Fix performance problem with new COPY DEFAULT code

  6. hio: Use ExtendBufferedRelBy() to extend tables more efficiently

  7. Add VACUUM/ANALYZE BUFFER_USAGE_LIMIT option