This paper describes the evolution of the Plan table and DBMSX_PLAN in 11g and some of the features that can be used to troubelshoot SQL performance effectively and efficiently.

1. Do you know the 11g Plan? Mahesh Vallampati

4. The Plan Table

6. Explain Plan Example - I select empno, ename, sal, deptno from emp where empno = 7654 ; ----------------------------------------------------------------------------------- |Id | Operation | Name |Rows|Bytes|Cost (%CPU)|Time | ----------------------------------------------------------------------------------- | 0| SELECT STATEMENT | | 1| 17| 1 (0)|00:00:01 | | 1| TABLE ACCESS BY INDEX ROWID| EMP | 1| 17| 1 (0)|00:00:01 | |* 2| INDEX UNIQUE SCAN | EMP_EMPNO_PK | 1| | 0 (0)|00:00:01 | ----------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - access("EMPNO"=7654)

7. Explain Plan Example - II select ename from emp where comm is not null; -------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 4 | 32 | 4 (0)| 00:00:01 | |* 1 | TABLE ACCESS FULL| EMP | 4 | 32 | 4 (0)| 00:00:01 | -------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter("COMM" IS NOT NULL)

10. Explain Plan Examples select empno, ename, sal, deptno from emp where empno = 7654 ; ----------------------------------------------------------------------------------- |Id | Operation | Name |Rows|Bytes|Cost (%CPU)|Time | ----------------------------------------------------------------------------------- | 0| SELECT STATEMENT | | 1| 17| 1 (0)|00:00:01 | | 1| TABLE ACCESS BY INDEX ROWID| EMP | 1| 17| 1 (0)|00:00:01 | |* 2| INDEX UNIQUE SCAN | EMP_EMPNO_PK | 1| | 0 (0)|00:00:01 | ----------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - access("EMPNO"=7654)

13. DBMS_XPLAN

19. DBMS_XPLAN.DISPLAY Output

20. DBMS_XPLAN Package - # of Procedures and Functions

22. V$ SQL_PLAN Views

23. V$SQL and Related views View Name Description V$SQL The SQL Statement that is being executed and its non-plan details V$SQL_PLAN Contains the execution plan information for each child cursor loaded in the library cache V$SQL_PLAN_STATISTICS* Provides execution statistics at the row source level for each child cursor V$SQL_PLAN_STATISTICS_ALL*(Merges V$SQL_PLAN_STATISTICS with V$SQL_AREA) Contains memory usage statistics for row sources that use SQL memory (sort or hash-join)

24. V$SQL – New Columns in 11g Column Data Type Comment TYPECHECK_MEM NUMBER ??? IS_BIND_SENSITIVE VARCHAR2(1) Indicates whether the cursor is bind sensitive (Y) or not (N). A query is considered bind-sensitive if the optimizer peeked at one of its bind variable values when computing predicate selectivities and where a change in a bind variable value may cause the optimizer to generate a different plan. IS_BIND_AWARE VARCHAR2(1) Indicates whether the cursor is bind aware (Y) or not (N). A query is considered bind-aware if it has been marked to use extended cursor sharing. The query would already have been marked as bind-sensitive. IS_SHAREABLE VARCHAR2(1) Indicates whether the cursor can be shared (Y) or not (N) SQL_PATCH VARCHAR2(30) SQL patch used for this statement, if any SQL_PLAN_BASELINE VARCHAR2(30) SQL plan baseline used for this statement, if any

25. V$SQL and Related views in 11g View Name 11g enhancement V$SQL_PLAN Added child address and timestamp column V$SQL_PLAN_STATISTICS* Added child address column V$SQL_PLAN_STATISTICS_ALL*(Merges V$SQL_PLAN_STATISTICS with V$SQL_AREA) Added child address column

27. Key Performance Takeaways

28. New in 11g

29. SQL Plan Baselines

34. Plan Output in XML Format

37. Still the good stuff…

38. Access Predicates / Filter Predicates

42. Query Blocks

46. DBMS_XPLAN.DISPLAY_AWR

49. DBMS_XPLAN.DISPLAY_SQLSET

52. DBMS_XPLAN.DISPLAY_CURSOR

59. Q & Q U E S T I O N S A N S W E R S