Re: WIP: generalized index constraints

On Tue, 2009-07-07 at 13:22 -0400, Tom Lane wrote:
> Also, if hash indexes were a realistic alternative to btree for this,
> we'd already have come up against the problem that the CONSTRAINT syntax
> doesn't provide any way to specify what kind of index you want to use
> underneath the constraint. I think it might be interesting to turn
> around Jeff's syntax sketch and provide a way to say that a CONSTRAINT
> declaration should depend on some previously added index, eg
> something like
>
> ALTER TABLE tab ADD CONSTRAINT UNIQUE (col1, col2) USING index
>

How about:

ALTER TABLE tab ADD INDEX CONSTRAINT [name]
(col1 [op], col2 [op]) USING index

And then just validate the constraint at creation time, and store the
information in pg_constraint.

Regards,
Jeff Davis