Wouldn't this be a problem only if new subn() could/would re-use an id? if new sub() generates a unique id, there would be no chance of two subn entries having the same id.
I'd thought that the ids of the sub_k tables were never generated independently, but rather they must pre-exist as values of the super_id column of the super table. After reading your post though, I'm no longer sure that this is what Kirwan had in mind... (He does not give any details at all on how the IDs should be created.)
If I understand you correctly, there should be a "business rule" *somewhere* that says that entries in the super table must *always* be created following these steps:
1. generate a new (unique) ID from a sequence super_seq;
2. insert a new entry in the super table having this (necessarily unique) ID in its super_id column;
3. insert a new entry in some some sub_k table, having this ID in its super_id column;
4. (somehow) disallow any subsequent updating of the super_id field of this newly-added sub_k table (although it could still be OK to delete a record from the super table, and cascade this to the appropriate record in some sub_k table).
I'm sure this sort of thing could be implemented in PostgreSQL, though I'd be hard-pressed to fill in the details. How much of this can be specified in the definitions (CREATE TABLE ...) of the tables? For example, (1) could be taken care of by defining the super_id column of the super table as a SERIAL. I imagine that (2) and (3) would have to be encapsulated in a "stored procedure" . Can (4) be implemented in the definitions of the tables?
