RE: CBO irregularity
- From: "Cary Millsap" <cary.millsap@xxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 8 Jun 2004 01:04:18 -0500
True. The Oracle kernel also collects this information when you use
dbms_stats.gather_database_stats.
Cary Millsap
Hotsos Enterprises, Ltd.
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Satheesh.Babu@xxxxxxxxxxxxxxxxxx
Sent: Tuesday, June 08, 2004 12:47 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: CBO irregularity
P3 of "db file scattered read" waits will show the size of the multiblock
read actually performed.
Thanks and Regards,
Satheesh Babu.S
Bangalore.
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Naveen, Nahata (IE10)
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 request?
Regards
Naveen
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