关于Oralce中的执行计划explain plan

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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】