Load Shedding for Window Joins on Multiple Data Streams

We consider the problem of semantic load shedding for continuous queries containing window joins on multiple data streams and propose a robust approach that is effective with the different semantic accuracy criteria that are required in different applications. In fact, our approach can be used to (i) maximize the number of output tuples produced by joins, and (ii) optimize the accuracy of complex aggregates estimates under uniform random sampling. We first consider the problem of computing maximal subsets of approximate window joins over multiple data streams. Previously proposed approaches are based on multiple pairwise joins and, in their load-shedding decisions, disregard the content of streams outside the joined pairs. To overcome these limitations, we optimize our load-shedding policy using various predictors of the productivity of each tuple in the window. To minimize processing costs, we use a fastand-light sketching technique to estimate the productivity of the tuples. We the...

• Type: Conference
• Year: 2007
• Where: ICDE
• Authors: Yan-Nei Law, Carlo Zaniolo
• Keywords: Database, ICDE 2007, Multiple Data Streams, Multiple Pairwise Joins, Window Joins