Re: A qsort template - Mailing list pgsql-hackers

From David Rowley
Subject Re: A qsort template
Date
Msg-id CAApHDvrxefqXu4df8ZvkTHKvHNiWYkpsANRGek3E93fXUEaw9Q@mail.gmail.com
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In response to Re: A qsort template  (John Naylor <john.naylor@enterprisedb.com>)
List 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



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