RE: Index sample size when gathering table statistics

Thank you Stefan. This is exactly what I was looking for.

Thanks
Amir
-----Original Message-----
From: Stefan Koehler <contact_at_soocs.de> Sent: Saturday, July 13, 2019 5:29 AM
To: Hameed, Amir <Amir.Hameed_at_xerox.com>; ORACLE-L <oracle-l_at_freelists.org> Subject: Re: Index sample size when gathering table statistics

Hello Amir,
I think these 2 blog posts might answer your question.

• https://blogs.oracle.com/optimizer/how-does-autosamplesize-work-in-oracle-database-11g (Section "Effect of auto sample size on index stats gathering")
• https://blogs.oracle.com/optimizer/how-does-auto_sample_size-work-in-oracle-database-12c (Section "Effect of auto sample size on index stats gathering")

However if you wanna know in detail you can also trace DBMS_STATS and have a look at your own ( https://www.pythian.com/blog/options-for-tracing-oracle-dbms_stats/ ).

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher Website: http://www.soocs.de
Twitter: _at_OracleSK

> "Hameed, Amir" <Amir.Hameed_at_xerox.com> hat am 12. Juli 2019 um 16:39 geschrieben:
>
> I am curious to know why Oracle is collecting statistics on indexes this way in 11.2.0.4 where it is using a sample size of 100% on some indexes and a very little sample size on the other.
>
> Thank you,
> Amir
†Ûiÿü0ÁúÞzX¬¶Ê+ƒün– {ú+iÉ^ Received on Wed Jul 17 2019 - 22:53:40 CEST