| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | John Naylor <john(dot)naylor(at)enterprisedb(dot)com> |
| Cc: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: A qsort template |
| Date: | 2022-01-19 02:57:45 |
| Message-ID: | CAH2-WzmFuVN5P-LqwunMGzjfQDvCfn11g8qfh4MbGW0pvo4Deg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jan 18, 2022 at 6:39 PM John Naylor
<john(dot)naylor(at)enterprisedb(dot)com> wrote:
> Editorializing the null position in queries is not very common in my
> experience. Not null is interesting since it'd be trivial to pass
> constant false to the same Apply[XYZ]SortComparator() and let the
> compiler remove all those branches for us. On the other hand, those
> branches would be otherwise predicted well, so it might make little or
> no difference.
If you were going to do this, maybe you could encode NULL directly in
an abbreviated key. I think that that could be made to work if it was
limited to opclasses with abbreviated keys encoded as unsigned
integers. Just a thought.
--
Peter Geoghegan
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