PARALLEL SORT-HASH OBJECT-ORIENTED COLLECTION JOIN ALGORITHMS FOR SHARED-MEMORY MACHINES

Abstract

Collection join queries are join queries based on collection attributes (i.e. non-atomic attributes), which are common in object-oriented databases. We have identified three different kinds of collection join queries, namely; cullection-equi join, collection-intersect join, and sub-collection join. In this paper, we propose parallel join algorithms for these three collection join query types based on a combination of sort and hash methods, which we call parallel sort-hash, collection join algorithms. The proposed join algorithms play an important role in parallel object-oriented query processing, due to their superiority over the conventional join methods which are usually in a form of relational division, and also the inefficiency of the original join predicate processing. In our implementation of these algorithms on a shared-memory machine, we show that the combination between sort and hash methods is proven to be better than the conventional sort-merge and nested-loop based parallel join processing