Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: db_file_mutliblock_read_count and physical IO

Re: db_file_mutliblock_read_count and physical IO

From: Ron Rogers <RROGERS_at_galottery.org>
Date: Wed, 18 Aug 2004 11:00:10 -0400
Message-Id: <s12336d4.017@galottery.org>


Ryan,
 Was the data retrieved less than or equal to 8k? If it was than the I/O should be the same as it will only retrieve the data that is needed no matter what the db_file_multiblock_read_count(MBRC) is. Try the same test making sure that the data you need it larger than the MBRC and compare the results.
Just a thought.
Ron

>>> ryan.gaffuri_at_comcast.net 08/18/2004 10:25:17 AM >>>
I did a 10046 trace and verified that I can get up to 128 blocks/IO with db_file_multiblock_read_count.
How do I metric this? I look at my total physical IOs when I did a tkprof report and my total number of physical IOs remained the same when I had the value set to 8 as when I had it set to 128? Before I did this test, my assumption was: 'Oracle would do less total Physical IOs since I am retrieving more blocks per IO.'
That assumption proved false. Can someone explain why?



Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html 
-----------------------------------------------------------------
----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org
put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
Received on Wed Aug 18 2004 - 10:22:21 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US