查看oracle执行计划(命令实现)
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
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