Re: Showing I/O timings spent reading/writing temp buffers in EXPLAIN - Mailing list pgsql-hackers

From Michael Paquier
Subject Re: Showing I/O timings spent reading/writing temp buffers in EXPLAIN
Date
Msg-id Yk+fKeLkA7NuzxTS@paquier.xyz
Whole thread Raw
In response to Re: Showing I/O timings spent reading/writing temp buffers in EXPLAIN  (Masahiko Sawada <sawada.mshk@gmail.com>)
Responses Re: Showing I/O timings spent reading/writing temp buffers in EXPLAIN  (Michael Paquier <michael@paquier.xyz>)
List pgsql-hackers
On Thu, Apr 07, 2022 at 09:48:02PM +0900, Masahiko Sawada wrote:
> Oops, the results are opposite:
>
> HEAD: 5367.234 ms
> Patched: 5418.869 ms

I have been playing with external sorts & friends after running an
instance on scissors (fsync=off, PGDATA on tmpfs, etc.), even forcing
a compilation of the code with gettimeofday(), and I can see a
tendency of a ~1% impact with the patch in this configuration.  So
there is a tendency, while this is also rather close to the usual
noise range.  Anyway, this is going to be helpful for debugging when
temp file I/O is a bottleneck, so..  Applied 0001 with some tweaks to
the docs and some indentation fixes.

Now, 0002 is straight-forward but I need more coffee and lunch..
--
Michael

Attachment

pgsql-hackers by date:

Previous
From: Robert Haas
Date:
Subject: Re: pg14 psql broke \d datname.nspname.relname
Next
From: Thomas Munro
Date:
Subject: Re: Windows now has fdatasync()