Re: Inconsistent file IO times on AWR report
- From: Marcin Przepiorowski <pioro1@xxxxxxxxx>
- To: nkodner@xxxxxxxxx
- Date: Mon, 24 May 2010 16:22:56 +0100
On Mon, May 24, 2010 at 12:38 PM, Neil Kodner <nkodner@xxxxxxxxx> wrote:
> We enabled directIO and set filesystemIO_options to setall last week. Our
> first real test was this morning and our main batch jobs ran slower. A few
> things noticed was that there was more physical IO, and by looking at the
> tkprof (and soon 10046), the cardinality numbers on the explain plans for
> nearly all statements were much higher. The same plans were used but the
> cardinality numbers on the tkprof were much, much higher.
> I feel that this issue relates to optimizer stats and not a direct result of
> the parameter change but am not 100% sure. We haven't changed the way we
> analyze our tables in weeks.
Hi Neil
I doubt that changing filesystemIO_options has direct impact on
cardinality of joins or
selections.
Did you have any significant operations on OP_TRANSACTIONS table ?
In "before" example number of consistent reads is
72143 for table
51674 for index
Physical reads
12115 for table
1190 for index
In "after" example numbers are:
consistent reads:
191111 for table
128359 for index
Physical reads:
41166 for table
7420 for table
It look like size of table has been changed or additional CR are
related to consistent read (UNDO)
mechanism - is there a lot of transactions ?
regards,
--
Marcin Przepiorowski
http://oracleprof.blogspot.com
--
//www.freelists.org/webpage/oracle-l
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