Evaluating Window Joins over Unbounded Streams

We investigate algorithms for evaluating moving window joins over pairs of unbounded streams. We introduce a unit-time-basis cost model to analyze the expected performance of these algorithms. Using this cost model, we propose strategies for maximizing the efficiency of processing joins in three scenarios. First, we consider the case where one stream is much faster than the other. We show that an asymmetric combination of hash join and nested loops join (hash join on one input, nested loops join on the other) can outperform both the symmetric hash join and the symmetric nested loops join. Second, we investigate the case where system resources are insufficient to keep up with the input streams. We show that we can maximize the number of join result tuples produced in this case by properly allocating computing resources across the two inputs streams. Finally, we investigate strategies for maximizing the number of result tuples produced when memory is limited. We revisit the first two ca...

• Type: Conference
• Year: 2003
• Where: ICDE
• Authors: Jaewoo Kang, Jeffrey F. Naughton, Stratis Viglas
• Keywords: Database, ICDE 2003, Input Streams, Symmetric Hash Join, Symmetric Nested Loops