Black, Michael (IS) wrote: > I have a need to create a unique bi-directional relationship. > > You can think of it as pairings of people who eat dinner together. > > You can't guarantee that one column is less than the other so there's no win > there.
Why can't you have a well-known ordering for your values? It doesn't have to be meaningful, and it should be very easy. Do a sort on the binary representations if you don't have a better one. As long as you have that, put the value that orders first or equal in the same column all the time. Then have a unique key constraint over the pair of columns. Problem solved. > Speed is of the utmost concern here so fast is really important (how many > ways can I say that???). > > Is there anything clever here that can be done with indexes or such? Just what I said will do what you want and it is the simplest solution plus most efficient in both performance and disk usage. -- Darren Duncan _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
