On 01/26/2016 11:38 AM, Dane Foster wrote: > Hello, > > If I have a primary key index of the form: > (col1, col2, col3) > and a foreign key constraint of the form: > FOREIGN KEY (col1, col2) REFERENCES foo > ON DELETE CASCADE ON UPDATE CASCADE > should I create a separate index (col1, col2) or is PostgreSQL capable > of using the primary key's index?
You are not required to create one. foo(col1, col2) needs a unique index. There need not be any specific index on (col1, col2) in the referencing table. Whether you want one for performance depends on how selective (col1, col2) is without col3, and how large the table is. -- Josh Berkus Red Hat OSAS (opinions are my own) -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
