| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: memory layouts for binary search in nbtree |
| Date: | 2016-05-20 02:38:02 |
| Message-ID: | CAM3SWZQdEaEsZ62NopHB0uuw=kAqQ8MMeCTCDYSAt8=oVGyy9w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, May 18, 2016 at 6:25 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> currently we IIRC use linearly sorted datums for the search in
> individual btree nodes. Not surprisingly that's often one of the
> dominant entries in profiles. We could probably improve upon that by
> using an order more optimized for efficient binary search.
Did you ever try running a pgbench SELECT benchmark, having modified
things such that all PKs are on columns that are not of type
int4/int8, but rather are of type numeric? It's an interesting
experiment, that I've been meaning to re-run on a big box.
Obviously this will be slower than an equivalent plain pgbench SELECT,
but the difference may be smaller than you expect.
--
Peter Geoghegan
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