Hi Chris: On Thu, Dec 1, 2016 at 12:56 PM, Chris Withers <chris@xxxxxxxxxxxxxxxx> wrote: > So, first observation: if I make room nullable, the exclude constraint does > not apply for rows that have a room of null. I guess that's to be expected, > right? I would expect it, given: n=> select null=null, null<>null, not (null=null); ?column? | ?column? | ?column? ----------+----------+---------- | | (1 row) Those are nulls, BTW: n=> select (null=null) is null, (null<>null) is null, (not (null=null)) is null; ?column? | ?column? | ?column? ----------+----------+---------- t | t | t (1 row) I.e., the same happens with a nullable unique column, you can have one of each not null values and as many nulls as you want. SQL null is a strange beast. Francisco Olarte. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general