Re: Group-count estimation statistics

Manfred Koizar <mkoi-pg@aon.at>

From: Manfred Koizar <mkoi-pg@aon.at>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org
Date: 2005-01-31T19:35:25Z
Lists: pgsql-hackers
On Mon, 31 Jan 2005 11:20:31 -0500, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>Already done that way.
>            if (relvarcount > 1)
>                clamp *= 0.1;

That's not what I meant.  I tried to say that if we have a GROUP BY
several columns and one of these columns alone has more than N/10
distinct values, there's no way to get less than that many groups.

Servus
 Manfred