RE: CBO irregularity

  • From: <Satheesh.Babu@xxxxxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 8 Jun 2004 11:17:05 +0530

P3 of "db file scattered read" waits will show the size of the
multiblock read actually performed.


Thanks and Regards,

Satheesh Babu.S




From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Naveen, Nahata
Sent: Tuesday, June 08, 2004 10:49 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: CBO irregularity


        -          Make sure that your system statistics reasonably
represent the operational characteristics of your system. For example,
if your system really averages 3.7 blocks per multi-block read, then CBO
will make dumb decisions about whether to do full-table scans on systems
were db_file_multiblock_read_count=128.
        [Naveen Nahata] Can you please elaborate on how I can find, how
many blocks my system reads on an average per oracle multi-block read



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