Question

I’m building my first PostgreSQL database. Now it’s just two tables (table A with 1:N relation to table B). Table A has a non-deferrable primary key, while table B has a deferrable primary key. When I try to add table C with a foreign key pointing to primary key of table B (another 1:N relation), PgAdmin refuses to create the table and it returns an error message:

ERROR: cannot use a deferrable unique constraint for referenced table
“table_B”

From my previous searches deferrable primary key seemed to be normal solution. Is it really possible in PgAdmin? Do I need some special trick for this to run?

I use PostgreSQL 9.1.3 and PgAdmin III 1.14.3 on 32 bit Windows XP.

Answer 1

I believe it’s not possible. Quote from PostgreSQL docs about foreign key:

The referenced columns must be the columns of a non-deferrable unique
or primary key constraint in the referenced table.