| From: | Nathan Boley <npboley(at)gmail(dot)com> |
|---|---|
| To: | Willy-Bas Loos <willybas(at)gmail(dot)com>, postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: change sample size for statistics |
| Date: | 2011-06-10 20:07:19 |
| Message-ID: | BANLkTikkkzpxOuvkgiuMx0ywaHgq1u2jng@mail.gmail.com |
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| Lists: | pgsql-general pgsql-performance |
[ Sorry, forgot to cc list ]
>> It is said to be 10%. i would like to raise that, because we are getting bas
>> estimations for n_distinct.
>
> More to the point, the estimator we use is going to be biased for many
> ( probably most ) distributions no matter how large your sample size
> is.
>
> If you need to fix ndistinct, a better approach may be to do it manually.
>
> Best,
> Nathan
>
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