Changing a foreign key constraint?

Kind people,

I'd like to change a foreign key constraint, 'cause it's not doing the
right thing right now.

Example DDL's below...

CREATE TABLE foo (
foo_id SERIAL NOT NULL PRIMARY KEY
, ...
);

CREATE TABLE bar (
...
, foo_id INTEGER NOT NULL REFERENCES foo(foo_id)
...
);

I'd like to change that to

, foo_id INTEGER NOT NULL REFERNCES foo(foo_id) ON DELETE CASCADE

Is there any way to do this short of dropping & re-creating the db?

Big TIA for any hints, tips or pointers on this :)

Cheers,
D
--
David Fetter david(at)fetter(dot)org http://fetter.org/
phone: +1 510 893 6100 cell: +1 415 235 3778