Tom Lane <tgl@sss.pgh.pa.us> writes:
> Greg Stark <gsstark@mit.edu> writes:
> > Off the top of my head it seems the way to go about doing this would be to
> > simply not insert the records in the index until commit time. This doesn't
> > actually sound so hard, is there any problem with this approach?
>
> Yeah:
> begin;
> insert into foo (key, ...) values (33, ...);
> select * from foo where key = 33;
> ...
>
> If the SELECT uses an indexscan it will fail to find the just-inserted
> row.
Well presumably you would need a non-unique index created for query execution
purposes. The unique index would be purely for enforcing the constraint.
--
greg