On 2010-05-30 06:55 +0300, Robert Haas wrote:
> On Sat, May 29, 2010 at 11:40 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Yes, I've seen Jeff's example. It's a cute hack but somehow I doubt
>> that there is going to be a land rush to implement such things.
>> Can you point to any pre-existing example where anyone actually asked
>> for the ability to do that?
>
> I've often wished for the ability to constrain a tale to hold just one
> row, so I don't find that use case implausible at all.
As I pointed out in
http://archives.postgresql.org/pgsql-hackers/2010-05/msg01177.php , you
can already do that.
Having said that, I also think that supporting <> in exclusion
constraints would be useful. I can't come up with a real-world use case
right now though.
Regards,
Marko Tiikkaja