| From: | Joshua Tolley <eggyknap(at)gmail(dot)com> |
|---|---|
| To: | Hans-Jürgen Schönig <postgres(at)cybertec(dot)at> |
| Cc: | Dimitri Fontaine <dim(at)tapoueh(dot)org>, tgl(at)sss(dot)pgh(dot)pa(dot)us, heikki(dot)linnakangas(at)enterprisedb(dot)com, pgsql-hackers(at)postgresql(dot)org, zb(at)cybertec(dot)at |
| Subject: | Re: cross column correlation revisted |
| Date: | 2010-07-15 13:39:07 |
| Message-ID: | 4c3f0f7e.9f3ae70a.0ae9.2699@mx.google.com |
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| Lists: | pgsql-hackers |
On Thu, Jul 15, 2010 at 12:04:21PM +0200, Hans-Jürgen Schönig wrote:
> hello ...
>
> a view is already nice but i think it is still too narrow.
> the problem is: you don't want a view for every potential join.
> in addition to that - ideally there is not much left of a view when it comes to checking for costs.
> so, i think, this is not the kind of approach leading to total success here.
The prolem is a very big one, and it's helpful to try solving it one piece at
a time, so the single table and view-based cases are probably good starting
points.
> one side question: does anybody happen to know how this is one in oracle or db2?
Neither appear to handle multi-column statistics in any form.
[1] http://download.oracle.com/docs/cd/B13789_01/appdev.101/b10802/d_stats.htm
[2]
http://www.ibm.com/developerworks/data/library/techarticle/dm-0606fechner/index.html
--
Joshua Tolley / eggyknap
End Point Corporation
http://www.endpoint.com
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