Re: Proposal - improve eqsel estimates by including histogram bucket numdistinct statistics

From: Zeugswetter Andreas OSB sIT <Andreas(dot)Zeugswetter(at)s-itsolutions(dot)at>
To: Gregory Stark <stark(at)enterprisedb(dot)com>
Cc: Nathan Boley <npboley(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal - improve eqsel estimates by including histogram bucket numdistinct statistics
Date: 2008-06-10 10:16:59
Message-ID: 6DAFE8F5425AB84DB3FCA4537D829A561BBF8B9278@M0164.s-mxs.net
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> > I think for low ndistinct values we will want to know the exact
> > value + counts and not a bin. So I think we will want
> additional stats rows
> > that represent "value 'a1' stats".
>
> Isn't that what our most frequent values list does?

Maybe ? Do we have the relevant stats for each ?
But the trick is to then exclude those values from the histogram bins.

Andreas

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