Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 
Connected as test
 
SQL> create cluster hhh (n# integer) hash is n# hashkeys 256;
 
Cluster created
 
SQL> create table h1(n# integer, c# varchar2(100)) cluster hhh(n#);
 
Table created
 
SQL> create table h2(n# integer, k# integer, c# varchar2(100)) cluster hhh(n#);
 
Table created
 
SQL> create table h3(n# integer, k# integer, c# varchar2(100)) cluster hhh(n#);
 
Table created
 
SQL> alter table h1 add primary key(n#);
 
Table altered
 
SQL> alter table h2 add primary key(n#, k#);
 
Table altered
 
SQL> explain plan for select * from h1, h2 where h1.n# = h2.n#;
 
Explained
 
SQL> select * from table(dbms_xplan.display());
 
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 128377940
---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |     1 |   443 |    75   (0)| 00:00:01 |
|   1 |  NESTED LOOPS      |      |     1 |   443 |    75   (0)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| H1   |     1 |   215 |    75   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS HASH| H2   |     1 |   228 |            |          |
---------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
   3 - access("H1"."N#"="H2"."N#")
Note
-----
   - dynamic sampling used for this statement (level=2)
 
19 rows selected
 
SQL>