Oracle PL/SQL Tutorial/SQL PLUS Session Environment/EXPLAIN PLAN

Execution plan for the specified statement_id

SQL>
SQL> UNDEFINE v_statement_id;
SQL>
SQL> SELECT id ||
  2    DECODE(id, 0, "", LPAD(" ", 2*(level - 1))) || " " ||
  3    operation || " " ||
  4    options || " " ||
  5    object_name || " " ||
  6    object_type || " " ||
  7    DECODE(cost, NULL, "", "Cost = " || position)
  8  AS execution_plan
  9  FROM plan_table
 10  CONNECT BY PRIOR id = parent_id
 11  AND statement_id = "&&v_statement_id"
 12  START WITH id = 0
 13  AND statement_id = "&v_statement_id";
Enter value for v_statement_id:
old  11: AND statement_id = "&&v_statement_id"
new  11: AND statement_id = ""
old  13: AND statement_id = "&v_statement_id"
new  13: AND statement_id = ""
no rows selected
SQL>

Explain sql statement

SQL>
SQL> create table emp (
  2      EmpNo          NUMBER(10) primary key,
  3      Name           VARCHAR2(40),
  4      DeptNo         NUMBER(2),
  5      Salary         NUMBER(7,2),
  6      Birth_Date     DATE,
  7      Soc_Sec_Num    VARCHAR2(9),
  8      State_Code     CHAR(2)
  9  );
SQL>
SQL> explain plan
  2  set Statement_Id = "TEST"
  3  for
  4  select * from emp;
SQL>
SQL> select LPAD(" ",2*Level)||Operation||" "||Options||" "||Object_Name Q_Plan
  2  from PLAN_TABLE
  3  where Statement_Id = "TEST"
  4  connect by prior ID = Parent_ID and Statement_ID = "TEST"
  5  start with ID=0;
                                                              
Q_PLAN
------------------------------------------------------------------------------------------------------------------------
  SELECT STATEMENT
    TABLE ACCESS FULL EMP
    TABLE ACCESS FULL EMP
  SELECT STATEMENT
    TABLE ACCESS FULL EMP
    TABLE ACCESS FULL EMP
                    
SQL>
SQL> set autotrace off  explain
SQL>
SQL>
SQL> drop table emp;

SET AUTOTRACE TRACE EXP and EXPLAIN PLAN output

SQL>
SQL> select * from dual;
Execution Plan
----------------------------------------------------------
Plan hash value: 272002086
--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |     1 |     2 |     2   (0)| 00:00:01 |
|   1 |  TABLE ACCESS FULL| DUAL |     1 |     2 |     2   (0)| 00:00:01 |
--------------------------------------------------------------------------
SQL>
SQL> SET AUTOTRACE OFF
SQL>