From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Tiago Antão <tra(at)fct(dot)unl(dot)pt>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Optimisation deficiency: currval('seq')-->seq scan, constant-->index scan |
Date: | 2000-10-14 04:19:19 |
Message-ID: | 200010140419.AAA22701@candle.pha.pa.us |
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Lists: | pgsql-hackers |
> =?iso-8859-1?Q?Tiago_Ant=E3o?= <tra(at)fct(dot)unl(dot)pt> writes:
> > One thing it might be interesting (please tell me if you think
> > otherwise) would be to improve pg with better statistical information, by
> > using, for example, histograms.
>
> Yes, that's been on the todo list for a while.
>
> > There is a good article regarding this:
> > http://www.db2mag.com/summer00/programmer.shtml
>
> Interesting article. We do most of what she talks about, but we don't
> have anything like the ClusterRatio statistic. We need it --- that was
> just being discussed a few days ago in another thread. Do you have any
> reference on exactly how DB2 defines that stat?
>
Added to TODO:
* Keep statistics about clustering of table rows
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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