materialization with readonly transaction

SQL> WITH t AS (SELECT/*+ materialize */ LEVEL FROM dual WHERE 1=1 CONNECT BY level<=2)
  2  SELECT/*+ gather_plan_statistics */ * FROM t, t t2;

     LEVEL      LEVEL
---------- ----------
         1          1
         1          2
         2          1
         2          2

SQL> @LAST;

PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------------------------
SQL_ID  d5s46t4rq3j2u, child NUMBER 0
-------------------------------------
WITH t AS (SELECT/*+ materialize */ LEVEL FROM dual WHERE 1=1 CONNECT
BY level<=2) SELECT/*+ gather_plan_statistics */ * FROM t, t t2

PLAN hash VALUE: 3355184302

-------------------------------------------------------------------------------------------------------------
| Id  | Operation                       | Name                       | E-ROWS |E-Bytes| COST (%CPU)| A-ROWS |
-------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                |                            |        |       |     6 (100)|      4 |
|   1 |  TEMP TABLE TRANSFORMATION      |                            |        |       |            |      4 |
|   2 |   LOAD AS SELECT                |                            |        |       |            |      0 |
|*  3 |    FILTER                       |                            |        |       |            |      2 |
|   4 |     CONNECT BY WITHOUT FILTERING|                            |        |       |            |      2 |
|   5 |      FAST DUAL                  |                            |      1 |       |     2   (0)|      1 |
|   6 |   MERGE JOIN CARTESIAN          |                            |      1 |    26 |     4   (0)|      4 |
|   7 |    VIEW                         |                            |      1 |    13 |     2   (0)|      2 |
|   8 |     TABLE ACCESS FULL           | SYS_TEMP_0FD9D6600_718D03A |      1 |    13 |     2   (0)|      2 |
|   9 |    BUFFER SORT                  |                            |      1 |    13 |     4   (0)|      4 |
|  10 |     VIEW                        |                            |      1 |    13 |     2   (0)|      2 |
|  11 |      TABLE ACCESS FULL          | SYS_TEMP_0FD9D6600_718D03A |      1 |    13 |     2   (0)|      2 |
-------------------------------------------------------------------------------------------------------------

SQL> SET TRANSACTION read only;

TRANSACTION SET.

SQL> WITH t AS (SELECT/*+ materialize */ LEVEL FROM dual WHERE 1=1 CONNECT BY level<=2)
  2  SELECT/*+ gather_plan_statistics 2*/ * FROM t, t t2;

     LEVEL      LEVEL
---------- ----------
         1          1
         1          2
         2          1
         2          2

SQL> @LAST;

PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------------------------
SQL_ID  ax55p0ncc0w84, child NUMBER 0
-------------------------------------
WITH t AS (SELECT/*+ materialize */ LEVEL FROM dual WHERE 1=1 CONNECT
BY level<=2) SELECT/*+ gather_plan_statistics 2*/ * FROM t, t t2

PLAN hash VALUE: 1484617936

-------------------------------------------------------------------------------------------------------------
| Id  | Operation                       | Name                       | E-ROWS |E-Bytes| COST (%CPU)| A-ROWS |
-------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                |                            |        |       |     6 (100)|      4 |
|   1 |  TEMP TABLE TRANSFORMATION      |                            |        |       |            |      4 |
|   2 |   LOAD AS SELECT                |                            |        |       |            |      0 |
|*  3 |    FILTER                       |                            |        |       |            |      2 |
|   4 |     CONNECT BY WITHOUT FILTERING|                            |        |       |            |      2 |
|   5 |      FAST DUAL                  |                            |      1 |       |     2   (0)|      1 |
|   6 |   MERGE JOIN CARTESIAN          |                            |      1 |    26 |     4   (0)|      4 |
|   7 |    VIEW                         |                            |      1 |    13 |     2   (0)|      2 |
|   8 |     TABLE ACCESS FULL           | SYS_TEMP_0FD9D6601_718D03A |      1 |    13 |     2   (0)|      2 |
|   9 |    BUFFER SORT                  |                            |      1 |    13 |     4   (0)|      4 |
|  10 |     VIEW                        |                            |      1 |    13 |     2   (0)|      2 |
|  11 |      TABLE ACCESS FULL          | SYS_TEMP_0FD9D6601_718D03A |      1 |    13 |     2   (0)|      2 |
-------------------------------------------------------------------------------------------------------------

SQL> roll;
ROLLBACK complete.