On Sun, Dec 20, 2015 at 10:27:35PM +1300, David Rowley wrote: > On 16 December 2015 at 13:26, Simon Riggs <si...@2ndquadrant.com> wrote: > > > 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. > > > That does sound interesting, but it's important to remember that > referenced tables are not updated in real time in that same way that > indexes are.
Is getting them so even remotely possible, given the system we have now? Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
