Peter,
> I suppose a more constructive point would be, where are the other
> constraint types kept track of?
AFAICT, we're not tracking them in pg_class at all anymore, except that
FKs will set relhastrigger=true in the absensce of any other triggers.
The confusion on this particular line is caused by the "see
pg_constraint catalog", which covers *all* constraints, whereas
relconstrains only counts the CHECK constraints and not other types.
That's why I think a small emphasis on CHECK would prevent people from
being confused again.
Of course, at this point, we've spent more time discussing the issue
than people have been confused by it, probably.
--Josh