Oracle Database Discussions

We are able to use DBMS_METADATA.GET_DDL to extract the DDL for other objects including PK constraints but not for an FK constraint. It returns ORA-31603 as seen below.
In this example we are logged in as the user U1, who has the been granted the DBA role, and are creating objects in the U1 schema to illustrate the point that we are not dealing with a permissions issue. If we do this as the SYS user we get the same error.


-- ============= START EXAMPLE =============
SQL>
SQL>show user
USER is "U1"
SQL>
SQL>-- create 1st tbl
SQL>create table U1.TBL1 (COL1 number, COL2 varchar2(10));

Table created.

SQL>
SQL>-- create PK on 1st tbl
SQL>alter table U1.TBL1
2 add constraint PK_TBL1
3 primary key (COL1);

Table altered.

SQL>
SQL>-- create 2nd tbl
SQL>create table U1.TBL2 (COL1 number, COL2 varchar2(10));

Table created.

SQL>
SQL>-- create PK on 2nd tbl
SQL>alter table U1.TBL2
2 add constraint PK_TBL2
3 primary key (COL1);

Table altered.

SQL>
SQL>-- create FK on 1st tbl referencing 2nd tbl
SQL>alter table U1.TBL1 add constraint FK1_TBL1 foreign key (COL1) references U1.TBL2 (COL1);

Table altered.

SQL>
SQL>-- generated DDL for PK on 1st tbl
SQL>select dbms_metadata.get_ddl('CONSTRAINT','PK_TBL1','U1') from dual;

DBMS_METADATA.GET_DDL('CONSTRA
________________________________________

ALTER TABLE "U1"."TBL1" ADD CONSTRAINT "PK_TBL1" PRIMARY KEY ("COL1")
USIN
SQL>
SQL>-- generated DDL for FK on 1st tbl
SQL>select dbms_metadata.get_ddl('CONSTRAINT','FK1_TBL1','U1') from dual;
ERROR:
ORA-31603: object "FK1_TBL1" of type CONSTRAINT not found in schema "U1"
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 105
ORA-06512: at "SYS.DBMS_METADATA", line 2806
ORA-06512: at "SYS.DBMS_METADATA", line 4333
ORA-06512: at line 1

no rows selected

SQL>
-- ============= END EXAMPLE =============


If anyone has any suggestions they would be greatly appreciated.
Thanks