Re: Optimisation deficiency: currval('seq')-->seq scan, constant-->index scan

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Tiago Antão <tra(at)fct(dot)unl(dot)pt>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Optimisation deficiency: currval('seq')-->seq scan, constant-->index scan
Date: 2000-08-21 14:37:29
Message-ID: 1731.966868649@sss.pgh.pa.us
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=?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?

regards, tom lane

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