Re: Updating system catalogs after a tuple deletion

Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> writes:
> Actually this brings up a problem I'm having with ALTER TABLE ADD
> CONSTRAINT and since it mostly affects you with DROP CONSTRAINT, I'll
> bring it up here. If you have a table that has check constraints or
> is inherited from multiple tables, what's the correct way to name an
> added constraint that's being inherited? If it's $2 in the parent,
> but the child already has a $2 defined, what should be done? The
> reason this affects drop constraint is knowing what to drop in the
> child. If you drop $2 on the parent, what constraint(s) on the child
> get dropped?

Seems like depending on the name is inadequate. Perhaps a column should
be added to pg_relcheck to show that a constraint has been inherited.
Maybe "rcinherit" = OID of parent's equivalent constraint, or 0 if
constraint was not inherited. Then you could do the right things
without making any assumptions about constraint names being the same.

regards, tom lane