Idle idea for a feature

psql's \d command tells you about outgoing foreign key constraints
(ie, ones referencing another table from this one).  It doesn't tell
you about incoming ones (ie, ones where another table references this
one).  ISTM it'd be a good idea if it did, as "are there any incoming
foreign keys" seems to be a question we constantly ask when solving
update-performance problems, and there isn't any easy way to check for
such.  I'm not real sure what the printout should look like, though.
        regards, tom lane