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Home -> Community -> Mailing Lists -> Oracle-L -> RE: how to keep statistics up to date for CBO
Bob,
I do the following:
First, alter all tables turning monitoring on: alter table {table name} monitoring;
Monitoring says:
"Specify MONITORING if you want Oracle to collect modification statistics on
table. These statistics are estimates of the number of rows affected by DML
statements over a particular period of time. They are available for use by
the optimizer or for analysis by the user."
Then use the following. It recalculates stats for those tables that have been changed enough to warrant stats. The User_Tab_Modifications table will hold a record if 10% of the table was changed. I've been using this for a while now, and it seems to be working fine. As you can see, I have a database table that I insert a record into so I can see how much work is done. I'm happy with it. And I'm not gathering stats for tables that I don't need to. I run this job daily.
Hope this helps.
PROCEDURE WTWDBA.Wtw_Gather_Statistics IS
/*
Procedure Name : Wtw_Gather_Statistics
Author : Tom Mercadante Mercadante Systems Design June 14, 2001 Purpose :
This Package will use the System DBMS_STATS package to gather statistics for both tables and indexes.
*/
loc_table_name USER_TABLES.TABLE_NAME%TYPE; loc_index_name USER_INDEXES.INDEX_NAME%TYPE; tbl_count NUMBER := 0; indx_count NUMBER := 0;
CURSOR c1 IS
SELECT ut.table_name FROM USER_TABLES UT, USER_TAB_MODIFICATIONS UTM
WHERE UT.TABLE_NAME = UTM.table_name;
CURSOR c2 IS
SELECT index_name FROM USER_INDEXES
WHERE table_name = loc_table_name;
BEGIN loc_start_time := SYSDATE;
OPEN c1;
LOOP
FETCH c1 INTO loc_table_name;
EXIT WHEN c1%NOTFOUND; dbms_stats.gather_table_stats('WTWDBA',loc_table_name); tbl_count := tbl_count + 1;
END LOOP;
CLOSE c1;
SYSDATE,INITCAP('SCHEMA Stats Complete') ||
CHR(10) ||
tbl_count || INITCAP(' TABLES Analyzed ') ||
CHR(10) ||
indx_count || INITCAP(' INDEXES Analyzed'));COMMIT; END; Tom Mercadante
-----Original Message-----
Sent: Wednesday, October 08, 2003 4:54 PM
To: Multiple recipients of list ORACLE-L
How does one keep CBO statistics for an applications base tables up to date?
We are about to implement the CBO any must read documents.
Many thanks
bob
--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Bob Metelsky
INET: bmetelsky_at_cps92.com
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Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services ---------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Thu Oct 09 2003 - 07:59:33 CDT
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