1. set autotrace on and execute sql .
Using index by "INDEX RANGE SCAN"
2. Through AWR report found the sql is top1 in SQL ordered by CPU Time part.
3. alter session set events '10046 trace name context forever, level 8';
Execute sql again and found STAT line for the traced query contains 'cnt=xxx' problem.
4. Check table records found the value are skewed cause by program bug.
5. Remove abnormal data and analyze index column .
execute dbms_stats.gather_table_stats('xxx','xxxxxxx',method_opt=>'FOR COLUMNS xxx');
6. High CPU utilization was solved.
