16. The computer program product of claim 15 , wherein collisions encountered by the at least one multi-way hash join operation are resolved by buffering up document nodes having a specific hash value.
15. The computer program product of claim 13 , wherein the computer readable program causes the computing device to perform the index scan for each query leg of the plurality of query legs, and wherein results of the index scans of the plurality of query legs are joined using at least one hierarchical multi-way hash join operation that operates on the BUILD hash table and the PROBE hash table.