Re: WIP: Deferrable unique constraints

Jeff Davis <pgsql@j-davis.com> writes:
> On Tue, 2009-07-28 at 13:41 -0400, Tom Lane wrote:
>> I think we had better add the deferrability state to pg_index
>> to avoid this.

> This might make it difficult to allow multiple constraints to use the
> same index.

Huh?  That hardly seems possible anyway, if some of them want deferred
checks and others do not.

> I'm trying to figure out how this fits with the generalized index
> constraints idea. We may want the generalized index constraints to have
> the same "immediate" behavior, but that doesn't have much to do with the
> index.

Sure it does.  Whether the check is immediate must be considered a
property of the index itself.  Any checking you do later could be
per-constraint, but the index is either going to fail at insert or not.
        regards, tom lane