Greedy List Intersection

A common technique for processing conjunctive queries is to first match each predicate separately using an index lookup, and then compute the intersection of the resulting rowid lists, via an AND-tree. The performance of this technique depends crucially on the order of lists in this tree: it is important to compute early the intersections that will produce small results. But this optimization is hard to do when the data or predicates have correlation. We present a new algorithm for ordering the lists in an ANDtree by sampling the intermediate intersection sizes. We prove that our algorithm is near-optimal and validate its effectiveness experimentally on datasets with a variety of distributions.

• Type: Conference
• Year: 2008
• Where: ICDE
• Authors: Robert Krauthgamer, Aranyak Mehta, Vijayshankar Raman, Atri Rudra
• Keywords: Common Technique, Conjunctive Queries, Database, ICDE 2008, Intermediate Intersection Sizes