Re: [ADMIN] number of rows in analyze - Mailing list pgsql-general

From Willy-Bas Loos
Subject Re: [ADMIN] number of rows in analyze
Date
Msg-id CAHnozThf=1LgD-bRmGtX6hooS9RGyYqej4n91P4vGLGpafot1A@mail.gmail.com
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In response to Re: [ADMIN] number of rows in analyze  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Ok, so 300 times the statistics target!
Thanks a lot for the exact code and formula!

On Mon, Aug 1, 2011 at 4:49 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Why?  This is purely an implementation detail.  From the user's
> viewpoint, either the stats are good enough or they're not --- the exact
> number of rows sampled doesn't seem that interesting.
>
>                        regards, tom lane

Because the manual says that i can influence the number of rows that
are sampled by increasing the statistics target.
But i don't know how sensitive that value is, i want to know what it
is that i am about to do.

btw i don't like that the number of statistics records are coupled
with the number of rows sampled. it's not only confusing, it doesn't
seem optimal to me.
I guess i will look up the paper to find out more. I didn't make an
academic study about it (yet :P ) .

Cheers!

WBL



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