Explain PLAN ...en dos simples pasos..

DELETE PLAN_TABLE;
EXPLAIN PLAN FOR SELECT * FROM mierda;

Para ver el resultado:

Copiar

set pagesize 1000
set linesize 150
col objeto format a40
col operacion format a60

SELECT 
  SUBSTR (LPAD(' ', LEVEL-1) || OPERATION || ' (' || OPTIONS || ')',1,30 ) "OPERACION", 
  OBJECT_NAME "OBJETO"
FROM PLAN_TABLE 
START WITH ID = 0 
CONNECT BY PRIOR ID=PARENT_ID;