| From: | Hannu Krosing <hannu(at)skype(dot)net> |
|---|---|
| To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Cc: | pgsql-hackers(at)postgresql(dot)org, Perez <arturo(at)ethicist(dot)net> |
| Subject: | Re: An Idea for planner hints |
| Date: | 2006-08-14 20:41:29 |
| Message-ID: | 1155588089.2905.3.camel@localhost.localdomain |
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| Lists: | pgsql-hackers |
Ühel kenal päeval, E, 2006-08-14 kell 18:21, kirjutas Peter Eisentraut:
> Perez wrote:
> > I thought, from watching the list for a while, that the planner
> > statistics needed were known but that how to gather the statistics
> > was not?
>
> I think over the course of the discussion we have figured out that we
> would like to have cross-column correlation statistics. The precise
> mathematical incarnation hasn't been determined yet, as far as I can
> see. Collecting the statistics thereafter isn't that hard, but there
> needs to be a way to not collect an exponential volume of statistics on
> all column combinations.
I understood that the proposal was to collect only the stats where
needed (determined by user/dba) and use some rule-of-thumb values if no
collected stats were available.
--
----------------
Hannu Krosing
Database Architect
Skype Technologies OÜ
Akadeemia tee 21 F, Tallinn, 12618, Estonia
Skype me: callto:hkrosing
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