Re: Minor inheritance/check bug: Inconsistent behavior

On Thu, Sep 19, 2013 at 10:28 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> Marking this as Ready for committer.
>>
>> Thanks a ton for reviewing the patch.
>
> I rewrote the comments for this patch and fixed the incorrect
> formatting in parse_relation.c. It used spaces instead of tabs, which
> is why if you look at the patch file you'll see that the alignment
> looked off. See new version, attached.
Thanks, Attached version looks better.

> However, I have a few residual questions:
>
> 1. Does copy.c also need to be fixed? I see that it also calls
> ExecConstraints(), and I don't see it setting tableOid anywhere. We
> certainly want COPY and INSERT to behave the same way.

I have missed it by confusing it with OID, as OID is set in COPY.
I think along with COPY, it needs to set in ATRewriteTable() as well,
because during rewrite also we check constraints.

I will send an updated patch after point-2 is concluded.

>
> 2. Should constraints also allow access to the "oid" column? Right
> now you can do that but it doesn't seem to work, e.g.:
>
> rhaas=# create table foo (a int, check (oid::integer % 2 = 0)) with oids;
> CREATE TABLE

I have tried various combinations, it is giving error at my end.
postgres=# create table tbl_with_oid(c1 int) With OIDS;
CREATE TABLE
postgres=# alter table tbl_with_oid add check (oid < 16403);
ERROR: system column "oid" reference in check constraint is invalid
postgres=# alter table tbl_with_oid add check (oid =0);
ERROR: system column "oid" reference in check constraint is invalid
postgres=# alter table tbl_with_oid add check (oid::integer %2 =0);
ERROR: system column "oid" reference in check constraint is invalid
postgres=# create table foo (a int, check (oid::integer % 2 = 0)) with oids;
ERROR: system column "oid" reference in check constraint is invalid

> Just prohibiting that might be fine; it doesn't seem that useful
> anyway.

Currently only tableOid is allowed, other system columns should error
out due to below check:
+ /* In constraint check, no system column is allowed except tableOid */
+ if (pstate->p_expr_kind == EXPR_KIND_CHECK_CONSTRAINT &&
+ attnum < InvalidAttrNumber && attnum != TableOidAttributeNumber)

> But if we're setting the table OID, maybe we should set the
> OID too, and then just allow this.
It can be done for OID as well. I don't have any strong reason for
either doing or not doing it, if you think it can be of use then we
can add it.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com