Oracle: 获取执行计划

执行这样的SQL：

#1

explain plan for select * from student;

select * from table(dbms_xplan.display);

这样可以看到CBO估计出的值

#2

select /*+ gather_plan_statistics */ * from student where student_id < 3 and 1 = 2;

select sql_id from v$sql where sql_text like ‘
select /*+ gather_plan_statistics */ * from student where student_id < 3 and 1 = 2%’;

select * from table(dbms_xplan.display_cursor (
上一条语句查出的sql-id, null, ‘allstats’));

这样既可以看到CBO估计出的值，又可以看到运行时的统计值