David Fetter <[EMAIL PROTECTED]> writes: > On Fri, Jul 18, 2008 at 03:04:08PM +0200, Markus Schiltknecht wrote: >> But what do we have primary keys for, in the first place?
> We have them because people are used to thinking in terms of a > "PRIMARY KEY," not because that concept is actually distinguishable > from a non-partial UNIQUE NOT NULL constraint. No, we have them because the SQL standard actually assigns a distinct meaning to a primary key. (It's the default foreign key reference column(s) for the table --- and in that context it's clear that There Can Be Only One.) regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers