Horton

Re: A qsort template

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: John Naylor <john.naylor@enterprisedb.com>
Cc: Peter Geoghegan <pg@bowt.ie>, Thomas Munro <thomas.munro@gmail.com>, Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Robert Haas <rhaas@postgresql.org>
Date: 2022-04-12T00:40:45Z
Lists: pgsql-hackers 
On Mon, 11 Apr 2022 at 22:11, John Naylor <john.naylor@enterprisedb.com> wrote:
>
> On Mon, Apr 11, 2022 at 5:34 AM David Rowley <dgrowleyml@gmail.com> wrote:
>
> > With this particular test, v15 is about 15% *slower* than v14.  I
> > didn't know what to blame at first, so I tried commenting out the sort
> > specialisations and got the results in the red bars in the graph. This
> > made it about 7.5% *faster* than v14. So looks like this patch is to
> > blame.  I then hacked the comparator function that's used in the
> > specialisations for BIGINT to comment out the tiebreak to remove the
> > indirect function call, which happens to do nothing in this 1 column
> > sort case.  The aim here was to get an idea what the performance would
> > be if there was a specialisation for single column sorts. That's the
> > yellow bars, which show about 10% *faster* than master.
>
> Thanks for investigating! (I assume you meant 10% faster than v14?)

Yes, I did mean to say v14.   (I'm too used to comparing everything to master)

David

Commits

  1. Remove debug messages from tuplesort_sort_memtuples()

  2. Fix performance regression in tuplesort specializations

  3. Fix tuplesort optimization for CLUSTER-on-expression.

  4. Initial pgindent and pgperltidy run for v14.

  5. Specialize checkpointer sort functions.

  6. Use sort_template.h for qsort() and qsort_arg().

  7. Use sort_template.h for qsort_tuple() and qsort_ssup().

  8. Add sort_template.h for making sort functions.

  9. Use abbreviated keys for faster sorting of text datums.