Cuando ejecutas el EXPLAIN la informacion la madas a una tabla que es esta:
CREATE TABLE plan_table
(statement_id VARCHAR2(30),
timestamp DATE,
remarks VARCHAR2(80),
operation VARCHAR2(30),
options VARCHAR2(30),
object_node VARCHAR2(128),
object_owner VARCHAR2(30),
object_name VARCHAR2(30),
object_instance NUMERIC,
object_type VARCHAR2(30),
optimizer VARCHAR2(255),
search_columns NUMERIC,
id NUMERIC,
parent_id NUMERIC,
position NUMERIC,
cost NUMERIC,
cardinality NUMERIC,
bytes NUMERIC,
other_tag VARCHAR2(255)
other LONG);
Ejecucion del EXPLAIN :
EXPLAIN PLAN
SET STATEMENT_ID = 'Emp_Sal'
FOR SELECT ename, job, sal, dname
FROM emp, dept
WHERE emp.deptno = dept.deptno
AND NOT EXISTS
(SELECT *
FROM salgrade
WHERE emp.sal BETWEEN losal AND hisal);
Para ver el resultado puede sutilizsar este query:
SELECT LPAD(' ',2*(LEVEL-1))||operation||' '||options
||' '||object_name
||' '||DECODE(id, 0, 'Cost = '||position) "Query Plan"
FROM plan_table
START WITH id = 0 AND statement_id = 'Emp_Sal'
CONNECT BY PRIOR id = parent_id AND statement_id ='Emp_Sal';
