In one embodiment, a system comprises a processor to retrieve a first data element including a value X0 and Y0, provide a hash function for use with a hash table having buckets, the hash function having a first and second input that in combination map to one of the buckets wherein the first input is in a range of X-values having X-value sub-ranges, the second input is in a range of Y-values having Y-value sub-ranges, different combinations of the X-value sub-ranges and the Y-value sub-ranges map using the hash function to different buckets, and input the value X0 and Y0 into the hash function yielding an output which is indicative of a first bucket of the hash-table. Related apparatus and methods are also described.