Oracle does not use transitive closure to add additional predicate
create table a(val number);
create table b(val number);
explain plan for select * from a, b where a.val = b.val and a.val = 1;

Explained.

SQL&gt; select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 652036164

---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |     1 |    26 |     4   (0)| 00:00:01 |
|*  1 |  HASH JOIN         |      |     1 |    26 |     4   (0)| 00:00:01 |
|*  2 |   TABLE ACCESS FULL| A    |     1 |    13 |     2   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| B    |     1 |    13 |     2   (0)| 00:00:01 |
---------------------------------------------------------------------------


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

   1 - access("A"."VAL"="B"."VAL")
   2 - filter("A"."VAL"=1)
   3 - filter("B"."VAL"=1)

Note
-----
   - dynamic statistics used: dynamic sampling (level=2)


And the parameter:

SQL&gt; alter session set "_optimizer_generate_transitive_pred"=false;

Session altered.

SQL&gt; explain plan for select * from a, b where a.val = b.val and a.val = 1;

Explained.

SQL&gt; select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 652036164

---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |     1 |    26 |     4   (0)| 00:00:01 |
|*  1 |  HASH JOIN         |      |     1 |    26 |     4   (0)| 00:00:01 |
|*  2 |   TABLE ACCESS FULL| A    |     1 |    13 |     2   (0)| 00:00:01 |
|   3 |   TABLE ACCESS FULL| B    |     1 |    13 |     2   (0)| 00:00:01 |
---------------------------------------------------------------------------


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

   1 - access("A"."VAL"="B"."VAL")
   2 - filter("A"."VAL"=1)

Note
-----
   - dynamic statistics used: dynamic sampling (level=2)