On Thu, Sep 12, 2013 at 10:03 PM, <wangs...@highgo.com.cn> wrote: > Second, I tested the check and the foreign key constraint as your test > above. > And no error found, as fellow:
You're missing the point. Peter wasn't worried that your patch throws an error; he's concerned about the fact that it doesn't. In PostgreSQL, you can only create the following view because test1 has a primary key over column a: => create table test1 (a int constraint pk primary key, b text); => create view test2 as select a, b from test1 group by a; => alter table test1 drop constraint pk; The reason that, if the primary key weren't there, it would be ambiguous which row should be returned as among multiple values where a is equal and b is not. If you can disable the constraint, then you can create precisely that problem. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
