Search notes:

ORA-14039: partitioning columns must form a subset of key columns of a UNIQUE index

Create a partitioned table:
create table tq84_ora_14039 (
    id_a    integer,
    id_b    integer,
    val_1   varchar2(10),
    val_2   number(10),
    val_3   date
    --
--  constraint tq84_ora_14039 primary key (id_a, id_b) using index local -- <== Throws ORA-14039
--  constraint tq84_ora_14039 primary key (id_a, id_b)                   -- <== OK
)
partition by range(val_2) interval (100000)
(
   partition tq84_ora_14039_part_1 values less than (0)
)
;
Trying to create the following index results in ORA-14039: partitioning columns must form a subset of key columns of a UNIQUE index:
alter table tq84_ora_14039 add primary key(id_a, id_b) using index local;
This statement is OK:
alter table tq84_ora_14039 add primary key(id_a, id_b);
The following two primary keys would also be OK.
The first one would create a non-aligned, the second one an aligned primary key:
alter table tq84_ora_14039 add primary key (val_1, val_2) using index local;
alter table tq84_ora_14039 add primary key (val_2, val_1) using index local;
Check alignment of indexes:
select alignment from user_part_indexes where table_name = 'TQ84_ORA_14039';
Cleaning up
drop table tq84_ora_14039;

See also

Other Oracle error messages

Index