db file parallel read for prefetching?

From: zhu chao <zhuchao_at_gmail.com>
Date: Mon, 21 Nov 2005 01:04:33 -0800
Message-ID: <962cf44b0511210104p55483287y1c11ceca3b098553@mail.gmail.com>

hi, all,

Does anyone has document/note talking about the index prefetching? I saw a few doc talking about oracle 9i introduced this feature, but no doc really talked, how it works, and how to enable/hint the prefetch for the optimizer, and how to verify it is working.

I have two database with identical hardware/schema, and some SQL with identical plan (and nearly same data volume), SQL in one database always run at 1/2 time of the other database.

I checked the 10046 trace and found the database faster has pretty much "db file parallel read" and the other instance is all "db file sequential read". I guess it is related to the prefetch, but do not have much detail about it.

If someone has some experience it, can you share?

--

Regards
Zhu Chao
www.cnoug.org
--

http://www.freelists.org/webpage/oracle-l Received on Mon Nov 21 2005 - 03:06:34 CST