On Sun, May 30, 2010 at 10:01 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Marko Tiikkaja <marko.tiikk...@cs.helsinki.fi> writes: >> On 2010-05-30 06:55 +0300, Robert Haas wrote: >>> 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. > > Yes. This is NOT about constraining a table to hold only one row. > It's about requiring all its rows to hold the same value (in some > column(s)), without predetermining exactly which value that will be. > I think the use-case for that is really extremely narrow.
It probably is pretty narrow. After all, exclusion constraints in general are something that not everyone needs, and the ordinary use case of preventing two intervals or regions from overlapping will doubtless be far more common than this one. Still, I'm not sure how that's relevant. The fact that not very many people will want to do something is not a reason to prevent it. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
