20170828索引监控

关于是否用到索引，可以在业务周期内对索引进行监控；

SELECT * FROM v$object_usage;
ALTER INDEX idx_emp_1 MONITORING USAGE;
ALTER INDEX idx_emp_2 MONITORING USAGE;
SELECT * FROM v$object_usage;
SELECT * FROM emp WHERE empno = '0';
SELECT * FROM v$object_usage;
ALTER INDEX idx_emp_1 NOMONITORING USAGE;
ALTER INDEX idx_emp_2 NOMONITORING USAGE;
SELECT * FROM v$object_usage;