关于Oralce中的执行计划explain plan

SQL> explain plan for select a.object_id from docversion a,generic b where a.object_id = b.object_id;

Explained

SQL> select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
----------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
----------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | |
| 1 | NESTED LOOPS | | | | |
| 2 | TABLE ACCESS FULL | GENERIC | | | |
|* 3 | INDEX UNIQUE SCAN | SYS_C0054740 | | | |
----------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - access("A"."OBJECT_ID"="B"."OBJECT_ID")
Note: rule based optimization

16 rows selected
编写于【2009-01-15】 阅读更多