CAM conscious integrated answering of frequent elements and top-k queries over data streams

Abstract

Frequent elements and top-k queries constitute an important class of queries for data stream analysis applications. Certain applications require answers for both frequent elements and top-k queries on the same stream. In addition, the ever increasing data rates call for providing fast answers to the queries, and researchers have been looking towards exploiting specialized hardware for this purpose. Content Addressable Memory(CAM) provides an efficient way of looking up elements and hence are well suited for the class of algorithms that involve lookups. In this paper, we present a fast and efficient CAM conscious integrated solution for answering both frequent elements and top-k queries on the same stream. We call our scheme CAM conscious Space Saving with Stream Summary (CSSwSS), and it can efficiently answer continuous queries. We provide an implementation of the proposed scheme using commodity CAM chips, and the experimental evaluation demonstrates that not only does the proposed scheme outperforms existing CAM conscious techniques by an order of magnitude at query loads of about 10%, but the proposed scheme can also efficiently answer continuous queries.