Database Software

Hello,

I have a table that is version-enabled and i want to change a column from NOT NULL to NULLABLE.
When i try to do the operation, i get the error "ORA-01451: column to be modified to NULL cannot be modified to NULL".
The code i'm running is something like this:

-- Create test tables

create table test1 (
id number(1),
something varchar2(50)
);

create table test2 (
id number(1),
other_id number(1) NOT NULL
);

-- Create PKs and FK
alter table test1 add constraint test1_pk primary key (id);
alter table test2 add constraint test2_pk primary key (id);
alter table test2 add CONSTRAINT test2_fk foreign key (other_id) references test1 (id);

-- Version-enable both tables
begin
dbms_wm.enableversioning('test1,test2');
end;

-- Start DDL session
begin
dbms_wm.beginddl('test2');
dbms_wm.beginddl('test1');
end;

-- Modify column
alter table test2_lts modify (other_id number(1) null);

-- Commit DDL session
begin
dbms_wm.commitddl('test2');
dbms_wm.commitddl('test1');
end;
(...)

Looking at the possible causes of this error:
(1) - column already allows NULL values;
(2) - the column is used in a primary key or check constraint and can not accept NULL values;

When i get the details for table TEST2_LTS, the column 'other_id' is already nullable, so the problem is obviously (1).
However, column 'other_id' is set to NOT NULL in table TEST2_LT.
I also tried the opposite operation - start with field nullable and then set to not null - and there is no problem.

Why this difference occurs? Is supposed to happen? How can I solve this problem?
Thanks.
Best regards,

Pedro Lourenço