Re: number of rows in analyze

From: "ktm(at)rice(dot)edu" <ktm(at)rice(dot)edu>
To: Willy-Bas Loos <willybas(at)gmail(dot)com>
Cc: pgsql-general(at)postgresql(dot)org, pgsql-admin <pgsql-admin(at)postgresql(dot)org>
Subject: Re: number of rows in analyze
Date: 2011-08-01 14:49:12
Message-ID: 20110801144912.GB26302@staff-mud-56-27.rice.edu
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-admin pgsql-general

On Mon, Aug 01, 2011 at 04:42:23PM +0200, Willy-Bas Loos wrote:
> Hi,
>
> I'ver been wondering how to set the number of rows that are scanned by
> analyze. (I want to increase it)
> I couln't find it at first but when i read closer i found that is does:
> "The largest statistics target among the columns being analyzed
> determines the number of table rows sampled to prepare the
> statistics."
> (http://www.postgresql.org/docs/8.4/interactive/sql-analyze.html)
>
>
> My question is *HOW* does it "detirmine the number of table rows
> sampled" with the statistics target?
> What is the formula behind it?
>
> I am not familiar enough with the source code to figure that out
> myself. sry about that.
> Would be good to include in the docs if we find out.
>
> Cheers,
>
> WBL
>
Peruse the above reference a bit more carefully. It is actually
explained pretty well.

Regards,
Ken

In response to

Browse pgsql-admin by date

  From Date Subject
Next Message Tom Lane 2011-08-01 14:49:59 Re: number of rows in analyze
Previous Message Willy-Bas Loos 2011-08-01 14:42:23 number of rows in analyze

Browse pgsql-general by date

  From Date Subject
Next Message Tom Lane 2011-08-01 14:49:59 Re: number of rows in analyze
Previous Message Willy-Bas Loos 2011-08-01 14:42:23 number of rows in analyze