Oracle Database Discussions

Hi all,

Here is a query containing a window function rank(). Can anybody tell me what does WINDOW SORT mean? Does it mean a sorting plus a window function evaluation?

SQL> EXPLAIN PLAN FOR
2 select wf.*, rank()over(partition by age order by id) from wf;
SQL> SELECT PLAN_TABLE_OUTPUT FROM TABLE(DBMS_XPLAN.DISPLAY());

---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time|
---------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 26 | 3 (34)| 00:00:01 |
| 1 | WINDOW SORT | | 1 | 26 | 3 (34)| 00:00:01 |
| 2 |TABLE ACCESS FULL | WF | 1 | 26 | 2 (0)| 00:00:01 |
---------------------------------------------------------------------------

Thanks,
Li Jie