I'm a newbie in Oracle 11g and that i have one question concerning the execution plan. I went a question and despite the fact that there's no ORDER BY clause within the query, the data around the execution plan still implies that you will find 6 sorts in memory. Can anybody please show me why this happened? Below may be the query and also the statistics:

SQL> SELECT ZIP FROM NOZIPSORT WHERE ZIP BETWEEN '10000' AND '29999' AND rownum < 26;

25 rows selected.

Elapsed: 00:00:00.07

Execution Plan
----------------------------------------------------------
Plan hash value: 4176934817

--------------------------------------------------------------------------------
| Id  | Operation          | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |           |    25 |   150 |     2   (0)| 00:00:01 |
|*  1 |  COUNT STOPKEY     |           |       |       |            |          |
|*  2 |   TABLE ACCESS FULL| NOZIPSORT |    28 |   168 |     2   (0)| 00:00:01 |
--------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter(ROWNUM<26)
   2 - filter("ZIP"<='29999' AND "ZIP">='10000')


Statistics
----------------------------------------------------------
        311  recursive calls
          0  db block gets
         47  consistent gets
         38  physical reads
        520  redo size
        805  bytes sent via SQL*Net to client
        431  bytes received via SQL*Net from client
          3  SQL*Net roundtrips to/from client
          6  sorts (memory)
          0  sorts (disk)
         25  rows processed

I'd say it will likely be the recursive calls which are doing a bit of sorting - e.g. once the totally parsed, the information dictionary must be queried to determine the table and column definitions, and a few of these queries calls for DISTINCT or any other procedures that need sorting.