Check
http://petereisentraut.blogspot.com/2009/07/how-to-find-all-tables-without-primary.html
On Fri, 2010-01-15 at 11:39 -0500, akp geek wrote:
> Dear all -
>
> I have the following query to find the tables with
> primary keys. can you please help me finding the tables without
> primary key.
>
> select
> distinct x.table_name,
> from
> information_schema.constraint_column_usage x,
> pg_constraint b
> where
> b.contype='p' and
> x.constraint_name=b.conname
>
> Regards
>