Horton

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

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Dean Rasheed <dean.a.rasheed@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Masahiko Sawada <sawada.mshk@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>, Andrew Dunstan <andrew@dunslane.net>, Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-08-01T14:00:47Z
Lists: pgsql-hackers

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On Wed, 2 Aug 2023 at 01:26, Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>
> On Tue, 1 Aug 2023 at 13:55, David Rowley <dgrowleyml@gmail.com> wrote:
> >
> > I tried adding the "at least 1 digit check" by adding an else { goto
> > slow; } in the above code, but it seems to generate slower code than
> > just checking if (unlikely(ptr == s)) { goto slow; } after the loop.
> >
>
> That check isn't quite right, because "ptr" will not equal "s" if
> there is a sign character, so it won't detect an input with no digits
> in that case.

Ah, yeah. Thanks.

Here's a patch with an else condition when the first digit check fails.

master + fastpath4.patch:
latency average = 1579.576 ms
latency average = 1572.716 ms
latency average = 1563.398 ms

(appears slightly faster than fastpath3.patch)

David

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