Re: [PATCH] Equivalence Class Filters

There is an interesting real world case where we might get some use of these thoughts.

If we have Orders and OrderItems (FK->Orders)

and we also know (and can Assert) Order.order_date <= OrderItems.ship_date

then a restriction on Orders.order_date > X => OrderItem.ship_date > X when the two tables are joined on OrderId

and also a restriction on OrderItems.ship_date >= X => Orders.order_date < X when the two tables are joined on OrderId

Such an assertion could be checked during the FK check, so would not be expensive to maintain.

One for the future, at least, since we don't have any way of expressing or enforcing that just yet.