Yes, I remember using foreign key relationships to optimize symmetric hash join back when I worked on an OLAP db. The idea was that for a 1:1 relationship you c

Yes, I remember using foreign key relationships to optimize symmetric hash join back when I worked on an OLAP db. The idea was that for a 1:1 relationship you can immediately discard both sides of a joined tuple, while for a 1:many relationship you can immediately discard the "many" side of a joined tuple.