select dbms_metadata.get_ddl('INDEX','IDX_SP_OPP_ALL_FLAT1','DNA_OWNER')
from dual;

Error :
-----


ORA-31603: object "IDX_SP_OPP_ALL_FLAT1" of type INDEX not found in schema "DNA_OWNER"
ORA-06512: at "SYS.DBMS_METADATA", line 5088
ORA-06512: at "SYS.DBMS_METADATA", line 7589
ORA-06512: at line 1
31603. 00000 -  "object \"%s\" of type %s not found in schema \"%s\""
*Cause:    The specified object was not found in the database.
*Action:   Correct the object specification and try the call again.

select  index_name
from    all_indexes
where   table_name = 'DNA_SP_OPP_ALL_FLAT';


o/p

IDX_SP_OPP_ALL_FLAT1
IDX_SP_OPP_ALL_FLAT2
IDX_SP_OPP_ALL_FLAT3
IDX_SP_OPP_ALL_FLAT4

select  OWNER,
              index_name
from    all_indexes
where   INDEX_name = 'IDX_SP_OPP_ALL_FLAT1';

select  owner,index_name
from    all_indexes
where   table_name = 'DNA_SP_OPP_ALL_FLAT';


o/p >

OWNER            INDEX_NAME
------		--------------------
DNA_OWNER	IDX_SP_OPP_ALL_FLAT2
DNA_OWNER	IDX_SP_OPP_ALL_FLAT3
DNA_OWNER	IDX_SP_OPP_ALL_FLAT4
DNA_OWNER	IDX_SP_OPP_ALL_FLAT1