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;
loc_start_time DATE;
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;
-- Gather statistics on tables
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;
-- Gather statistics on indexes
OPEN c2;
LOOP
FETCH c2 INTO loc_index_name;
EXIT WHEN c2%NOTFOUND;
dbms_stats.gather_index_stats('WTWDBA',loc_index_name);
indx_count := indx_count + 1;
END LOOP;
CLOSE c2;
END LOOP;
CLOSE c1;
-- insert a record into the job log
INSERT INTO WTW_JOB_LOG(JOB_NAME, RUN_DATE, START_TIME,
END_TIME, MSG_TXT)
VALUES('Wtw_Gather_Statistics',SYSDATE,loc_start_time,
SYSDATE,INITCAP('SCHEMA Stats Complete') ||
CHR(10) ||
tbl_count || INITCAP(' TABLES Analyzed ') ||
CHR(10) ||
indx_count || INITCAP(' INDEXES Analyzed'));
COMMIT;
END;
Tom Mercadante
Oracle Certified Professional
-----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
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