At 01:45 PM 2/22/00 +0900, Tatsuo Ishii wrote:
>> Those are the two major user-visible loose ends with this feature.
>What about ALTER TABLE table DROP CONSTRAINT? I see this:
>
>alter table t1 drop constraint t1_fk cascade;
>ERROR: ALTER TABLE / DROP CONSTRAINT is not implemented
>
>Note that we seem to have ALTER TABLE table ADD CONSTRAINT, though.
"ALTER TABLE ... DROP CONSTRAINT" I view as being a more general
problem not simply restricted to referential integrity. My comment
was meant to be strictly interpreted within the realm of RI. Obviously,
general dropping of columns and constraints needs to be solved, but these
aren't RI issues specifically.
And, no, you don't have ALTER TABLE ... ADD CONSTRAINT. What you have
is the ability to add foreign key constraints only. When this was
added, we (Stephan Szabo, myself, and Jan Wieck) discussed doing
general constraints, too, but Jan pointed out that we were all busy
with RI-specific stuff and that we should concentrate on those issue.
A good call, IMO, as I was buried in trying to understand "NO ACTION"
and "MATCH <unspecified>" at the same; Stephan was working on pg_dump;
and Jan was really busy with his real job. I only had one weekend to
pour into implementing the proper semantics for the RI triggers, and
as a result of our decision to concentrate on RI-specific issues was
able to complete the necessary work for fully SQL92 compliant "MATCH
<unspecified>" foreign keys.
However, Stephan's ALTER TABLE ... work to allow you to add foreign
keys should be fairly easy to extend to general constraints, he and
Jan discussed this a couple of weeks ago.
7.1 would seem to be the likely target for this.
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