Design and Evaluation of Alternative Selection Placement Strategies in Optimizing Continuous Queries

In this paper, we design and evaluate alternative selection placement strategies for optimizing a very large number of continuous queries in an Internet environment. Two grouping strategies, PushDown and PullUp, in which selections are either pushed below, or pulled above, joins are proposed and investigated. While our earlier research has demonstrated that the incremental group optimization can significantly outperform an ungrouped approach, the results from this paper show that different incremental group optimization strategies can have significantly different performance characteristics. Surprisingly, in our studies, PullUp, in which selections are pulled above joins, is often better and achieves an average 10-fold performance improvement over PushDown (occasionally 100 times faster). Furthermore, a revised algorithm of PullUp, termed filtered PullUp is proposed that is able to further reduce the cost of PullUp by 75% when the union of the selection predicates is selective. Detail...

• Type: Conference
• Year: 2002
• Where: ICDE
• Authors: Jianjun Chen, David J. DeWitt, Jeffrey F. Naughton
• Keywords: Database, ICDE 2002, Incremental Group Optimization, Incremental Group Query, Selection Placement Strategies