Re: Group-count estimation statistics

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Group-count estimation statistics
Date: 2005-01-31 11:08:41
Message-ID: 294sv0tqnmfhofebc7q1qq12qisesv75l7@email.aon.at
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On Fri, 28 Jan 2005 10:53:33 -0500, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> we should consider
>something like "clamp to size of table / 10" instead.

... unless a *single* grouping column is estimated to have more than
N/10 distinct values, which should be easy to check.

Servus
Manfred

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