Oracle-L: RE: col_usage$ question

From: K Gopalakrishnan <kaygopal_at_yahoo.com>
Date: Tue, 18 Nov 2003 09:14:42 -0800
Message-ID: <F001.005D7100.20031118091442@fatcity.com>

Raj:

Wolfgang is right. It is populated by SMON (I think every 15mins SMON flushes the data to COL_USAGE) and the predicate columns are updated (or collected) from the hard parse of the SQLs.

Best Regards,
K Gopalakrishnan

-----Original Message-----
Wolfgang Breitling
Sent: Tuesday, November 18, 2003 8:59 AM To: Multiple recipients of list ORACLE-L

That is a new table in Oracle 9 and is used by Oracle to track what columns are used in predicates. At present the only use of that information that I am aware of is in the procedure dbms_stats.gather_table_stats ( ..., method_opt => 'for columns ... size auto');

At 09:29 AM 11/18/2003, you wrote:

>Does anyone know what this table (sys.col_usage$) is used for? To me it
>sounds like something that CBO might appreciate ... but any ideas? It is
>referenced by dbms_stats and dbms_stats_internal packages ...
>
>Thanks in advance
>Raj
>---------------------------------------------------------------------------

>
>Rajendra dot Jamadagni at nospamespn dot com

Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

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Received on Tue Nov 18 2003 - 11:14:42 CST