Poor index identify and resolve manually or using sql tuning advisor

1.Let us create a test case first:- oracle@TST:TESTDB1[/home/oracle]$ sqlplus c##test/test C##TEST@TESTDB1> create table mytst1 as select * from dba_objects; Table created. C##TEST@TESTDB1> create table mytst2 as select * from dba_objects where rownum<5000; Table created. 2.Let us see what application executes SQL query and complaining poor performance select a.owner,a.OBJECT_NAME,a.OBJECT_TYPE,b.STATUS from mytst1 a,mytst2 b where a.OBJECT_ID=b.OBJECT_ID and b.OBJECT_NAME=’DBA_TABLES’; 3.Now create an index […]

ORACLE OPTIMIZER COST CALCULATIONS BASIC OVERVIEW

Cost Calculation for Full table Scan How FTS cost depends on system statistics Gather statistics manually on load: The following command will start to gather system statistics. SQL> execute DBMS_STATS.GATHER_SYSTEM_STATS (‘START’); Please wait for system warm up and stop gather system statistics after work load. This is called workload statistics. The MBRC will be calculated automatically depending on no. of […]