如果在命令行中,建议使用这种方法.
set autotrace on
加上这个set命令后,执行任何SQL语句都会把执行计划和统计信息显示出来.
注意 : 这重方式每次都执行SQL语句,而下面的方法实际上并没有执行SQL语句.
看下面小练习,告诉你如何用oracle命令查看执行计划.
1.想要查看执法计划的SQL语句:
explain plan for select t.*, t.rowid from A5 t where t.l = '101214' and t.k like '%8号' order by i ;
2.查看此SQL语句的执行计划:
select * from table(dbms_xplan.display);
执行结果如下:
PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------- Plan hash value: 1156097717 --------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 12 | 1524 | 71 (3)| 00:00:01 | | 1 | SORT ORDER BY | | 12 | 1524 | 71 (3)| 00:00:01 | |* 2 | TABLE ACCESS FULL| A5 | 12 | 1524 | 70 (2)| 00:00:01 | ---------------------------------------------------------------------------- Note ----- - 'PLAN_TABLE' is old version 12 rows selected
'PLAN_TABLE' is old version : 这句话告诉我们,PLAN_TABLE的版本太旧,需要重新生成.
3.重新生成PLAN_TABLE表:
-- 删除表 drop table PLAN_TABLE; -- 新建表 @D:\oracle\product\10.2.0\db_1\RDBMS\ADMIN\utlxplan.sql;
4.查看执行计划:
select * from table(dbms_xplan.display);
结果如下:
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 1156097717
---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 12 | 1524 | 71 (3)| 00:00:01 |
| 1 | SORT ORDER BY | | 12 | 1524 | 71 (3)| 00:00:01 |
|* 2 | TABLE ACCESS FULL| A5 | 12 | 1524 | 70 (2)| 00:00:01 |
---------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("T"."L"='101214' AND "T"."K" LIKE '%8号')
14 rows selected