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: David Rowley <dgrowleyml@gmail.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, 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: 2023-07-25T16:06:35Z
Lists: pgsql-hackers 
Hi,

On 2023-07-25 08:50:19 -0700, Andres Freund wrote:
> One idea I had was to add a fastpath that won't parse all strings, but will
> parse the strings that we would generate, and fall back to the more general
> variant if it fails. See the attached, rough, prototype:
> 
> fix_COPY_DEFAULT.patch + fastpath.patch:
> 746.971
> 
> fix_COPY_DEFAULT.patch + fastpath.patch + isdigit.patch:
> 715.570
> 
> Now, the precise contents of this fastpath are not yet clear (wrt imul or
> not), but I think the idea has promise.

Btw, I strongly suspect that fastpath wants to be branchless SSE when it grows
up.

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