Re: db_file_mutliblock_read_count and physical IO
- From: "Ron Rogers" <RROGERS@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 18 Aug 2004 11:00:10 -0400
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@xxxxxxxxxxx 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?
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