SQL优化-1.查看解析计划

时间：2010-11-22 来源：x-i-x

SQL> explain plan for select a.name,b.id from a,b
2 where b.class=300 and a.name=b.name;

已解释。

SQL> select plan_table_output from table (dbms_xplan.display('plan_table',null,'serial'));

.... SQL> set linesize 3000;
SQL> / PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------ ---------------------------------------------------------------------------------------
| Id | Operation                   | Name               | Rows | Bytes | Cost (%CPU)|
---------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                    |    50 | 2450 |   144   (0)|
|   1 | TABLE ACCESS BY INDEX ROWID| B                |     1 |    25 |     3   (0)|
|   2 |   NESTED LOOPS              |                    |    50 | 2450 |   144   (0)|
|   3 |    TABLE ACCESS FULL        | A                  |    47 | 1128 |     3   (0)|
|* 4 |    INDEX RANGE SCAN         | Index_common_8     |     1 |       |     2   (0)|
--------------------------------------------------------------------------------------- Predicate Information (identified by operation id):
---------------------------------------------------    4 - access("B"."CLASS"=300 AND "A"."NAME"="B"."NAME") Note
-----
   - 'PLAN_TABLE' is old version