If they're not, the below causes problems, as the foreign key is added

If they're not, the below causes problems, as the foreign key is added
after the CHECK.  Cluster depends on the index name, so I thought it
wise to ensure all names are available, rather than leaving off the
CONSTRAINT "$n" portion for internally named constraints.

CREATE TABLE jkey (col integer primary key);
CREATE TABLE j (col integer REFERENCES jkey);
ALTER TABLE j ADD CHECK(col > 5);

This is a problem in 7.3 series as well as -Tip.

Rod Taylor <rbt@rbt.ca>