| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Alexander Korotkov <aekorotkov(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: GiST for range types (was Re: Range Types - typo + NULL string constructor) |
| Date: | 2011-11-03 08:42:29 |
| Message-ID: | 1320309749.32341.27.camel@jdavis |
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| Lists: | pgsql-hackers |
On Wed, 2011-11-02 at 22:59 +0200, Heikki Linnakangas wrote:
> This seems to be coming from the selectivity estimation function. The
> selectivity function for <@ is scalargtsel, which is usually used for
> scalar > and >=. That doesn't seem right. But what do we store in the
> statistics for range types in the first place, and what would be the
> right thing to do for selectivity estimation?
I'll have to think more about that, and it depends on the operator. It
seems like an easier problem for "contains a point" than "contains
another range" or "overlaps with another range".
Right now I don't have a very good answer, and even for the "contains a
point" case I'll have to think about the representation in pg_statistic.
Regards,
Jeff Davis
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