From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
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To: | Jeff Davis <pgsql(at)j-davis(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 11:59:56 |
Message-ID: | 4EB2823C.4010701@enterprisedb.com |
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Lists: | pgsql-hackers |
On 03.11.2011 10:42, Jeff Davis wrote:
> 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.
I've committed this now, after some more cleanup. I removed the
selectivity estimation functions from operators where they were bogus,
so writing those is a clear TODO. But that can well be done as a
separate patch.
Thanks!
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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