Preprocessing Method for Handling Multi-Way Join Continuous Queries over Data Streams

Abstract

A data stream is a series of tuples which are generated in real-time, incessant, immense, and volatile manner. As new information technologies are actively emerging, stream processing methods are being needed to efficiently handle data streams. Especially, finding out an efficient evaluation for a multi-way join would make outstanding contributions toward improving the performance of a data stream management system because a join operation is one of the most resource-consuming operators for evaluating queries.In this paper, in order to evaluate efficiently a multi-way join continuous query, we propose a novel method to decrease the cost of a query by eliminating unsuccessful intermediate results. For this, we propose a matrix-based structure for monitoring data streams and estimate the number of final result tuples of the query and find out unsuccessful tuples by matrix multiplication operations. And then using these information, we process efficiently a multi-way join continuous query by filtering out the unsuccessful tuples in advance before actual evaluation of the query. ☞ keyword : 데이터 스트림(data stream), 질의 처리(query processing), 조인 연산(join operation) 1. 서 론 최근 고도산업사회에 접어들면서 과학 기술이나 공학 분야 이외에 경제‧사회 등의 다양한 분야에서도 각종 데 이터들의 중요성이 강조되고 있으며, 데이터 종류의 다