It surprises me that no SQL database to my knowledge has polymorphic joins as a first-class feature.
A polymorphic join is where a fk contains not just an id but an indicator of which table it refers to. So you could have a "tags" table, that can attach tags to any of a variety of other tables. Rails handles this by including the table name as a string. This seems a reasonable thing to want to do, and it seems that the database could handle it by combining the fields from the target tables in the result. I also think migrations ought to be a first-class feature… -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
