| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Jeremy Harris <jgh(at)wizmail(dot)org> |
| Cc: | Arthur Silva <arthurprs(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Abbreviated keys for text cost model fix |
| Date: | 2015-03-03 17:56:12 |
| Message-ID: | CAM3SWZTYVuaWG5gR3tpE9eRigpi78TFs0T9FJmYisX9pBM=eRw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Mar 3, 2015 at 2:00 AM, Jeremy Harris <jgh(at)wizmail(dot)org> wrote:
> Yes; there seemed no advantage to any additional complexity.
> The merge consistently performs fewer comparisons than the
> quicksort, on random input - and many fewer if there are
> any sorted (or reverse-sorted) sections. However, it also
> consistently takes slightly longer (a few percent). I was
> unable to chase this down but assume it to be a cacheing
> effect. So I don't currently think it should replace the
> current sort for all use.
It's definitely caching effects. That's a very important consideration here.
--
Peter Geoghegan
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