considering i have two views x,y both with a property z, which is sorted in both views,
i would excpect joins or intersections on this property to be very fast. unfortunally in reality, the intersection of two sorted views with 1.000.000 integers takes several long seconds.
MK does not know it's sorted and re-sorts both views when joining.
Intersection is implemented by doing Counts(), then selecting items with count 2, then projecting away the added count field. Count in turn, uses a variant of Groupby, which sorts the view first - so as you can see it's quite general and I'm sure one could find better approaches for specific cases.
are there any suggestions on how to improve performance for intersections of sorted properties?
I can't think of any right now. You could look at the implementations (you don't mention which language you use) and see if you can come up with a special-cased version. There are no doubt ways to improve it, especially if the key is unique, i.e. the join is never to more than 1 row. Especially constructs using RemapWith() are worth looking into (and perhaps Concat or Pair).
-jcw
_______________________________________________ metakit mailing list - [EMAIL PROTECTED] http://www.equi4.com/mailman/listinfo/metakit
