How to set autotrace to explain plan ONLY

Question

Hi,
I would like to see explain plan for a long running statement.
Now if I do following:
set autotrace on explain
UPDATE ......-- my statement
I get the plan, but the rows are updated also :-(
Is there a way to tell ORACLE, please show me the explain plan but dio not execute the statement?
Thanks

Answer 1

ONLY FOR queries you can use
set autotrace traceonly explain
And actually query isn't executed. For other DML you cannot use that.
The other way can be explaining the query and then selecting the plan_table output:
SQL> explain plan for update t set code = 3;
Explained.
SQL> SELECT * FROM table(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value: 931696821
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | UPDATE STATEMENT   |      |     3 |     9 |     3   (0)| 00:00:01 |
|   1 |  UPDATE            | T    |       |       |            |          |
|   2 |   TABLE ACCESS FULL| T    |     3 |     9 |     3   (0)| 00:00:01 |
Note
PLAN_TABLE_OUTPUT
   - dynamic sampling used for this statement
13 rows selected.
SQL> see http://download-uk.oracle.com/docs/cd/B19306_01/appdev.102/b14258/d_xplan.htm
Gints Plivna
http://www.gplivna.eu