Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

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SQL> -- create table detail (id integer, master_id integer references master);
SQL> create table detail (id integer, master_id integer);

Table created.

SQL> insert into detail values (1, 1);

1 row created.

SQL> insert into detail values (2, 2);

1 row created.

SQL> insert into detail values (3, 4);

1 row created.

SQL> alter table detail add foreign key(master_id) references master novalidate;

Table altered.

SQL> explain plan for select d.* from detail d join master m on (d.master_id = m.id);

Explained.

SQL> select * from table(dbms_xplan.display());

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------

---------------------------------------------------------------------
| Id  | Operation          | Name      | Rows  | Bytes | Cost (%CPU)|
---------------------------------------------------------------------
|   0 | SELECT STATEMENT   |           |     4 |   156 |     3   (0)|
|   1 |  NESTED LOOPS      |           |     4 |   156 |     3   (0)|
|   2 |   TABLE ACCESS FULL| DETAIL    |     3 |    78 |     3   (0)|
|*  3 |   INDEX RANGE SCAN | MASTER_PK |     1 |    13 |     0   (0)|
---------------------------------------------------------------------

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

   3 - access("D"."MASTER_ID"="M"."ID")

Note
-----
   - 'PLAN_TABLE' is old version

18 rows selected.

SQL> select d.* from detail d join master m on (d.master_id = m.id);

        ID  MASTER_ID
---------- ----------
         1          1
         1          1
         2          2