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Verify CBO [message #555345]

Wed, 23 May 2012 05:32

Jack14
Messages: 497
Registered: December 2011
Location: INDIA

Senior Member

Hi,

How to find out the database is using Cost based analyzer?

Currently database is set to ALL_ROWS.

SQL> show parameter optimizer_mode

NAME                                 TYPE        VALUE
------------------------------------ ----------- -----------
optimizer_mode                       string      ALL_ROWS
SQL>
SQL>

Thank you

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Re: Verify CBO [message #555354 is a reply to message #555345]

Wed, 23 May 2012 06:28

cookiemonster
Messages: 13920
Registered: September 2008
Location: Rainy Manchester

Senior Member

All_rows means CBO. Unless it's set to RULE it's using the CBO.
You can check by running explain plan on a query - if you get cost figures it's using the CBO. The RBO doesn't understand cost.

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