Re: Bug of ALTER TABLE DROP CONSTRAINT

Hi,

> > Considering the following sequence:
> > create table t(a int primary key);
> > alter table t drop constraint t_pkey;
> > insert into t values(null);
> > ERROR: null value in column "a" violates not-null constraint
> >
> > My question is, why "null" is not allowed to be inserted after primary
> key
> > constraint has been dropped.
>
> Making a column into the primary key forces the column to NOT NULL.
> You'll need to DROP NOT NULL separately.
>
> It's probably possible to beat on the code hard enough to fix this,

Yeah it will be a matter of finding the affected column entries and invoking
the removal of the not null entry from their corresponding pg_attribute
rows.

> but I'm not really sure there's much point, since the situation is
> rare and the workaround is easy.
>

Yeah and it is documented already. Although it is not obvious immediately
that a not-null attribute gets tagged onto the involved columns separately
for primary, unique-not-null types of constraints.

Regards,
Nikhils
--
http://www.enterprisedb.com