ylfink@water.UUCP (ylfink) (12/15/86)
Subject: CS, U of W, Dr. J. Han on "Handling Redundancy in the Processing of Recursive Database Queries", Wed., Dec. 17/86, 3:30. Newsgroups: uw.talks,ont.events Distribution: uw Keywords: Knowledge Base Seminar DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF WATERLOO SEMINAR ACTIVITIES KNOWLEDGE BASE SEMINAR - Wednesday, December 17, 1986. Dr. Jiawei Han of Northwestern University will speak on ``Handling Redundancy in the Processing of Recursive Database Queries''. TIME: 3:30 PM ROOM: MC 5158 ABSTRACT The elimination of redundant or duplicated database accessing is a challenging task in recursive query optimization. Redundancy may exist in the processing of recursive database queries at four different levels: precompilation level, iteration level, tuple processing level and file accessing level. Techniques for reduc- ing redundant work at each level are studied. In the precompilation level, the techniques discussed include the removal of redundant parts in a rule cluster, the simplification of complexity of rule clusters, and the sharing of common subexpressions among rules. At the iteration level, the techniques discussed are the use of frontier relations and the counting method. At the tuple processing level, we develop the techniques of merging and filtering to exclude processed drivers from database reaccessing. Finally, at the file accessing level, I/O cost can be further reduced by level relaxa- tion. We conclude that even for complex recursion, redundant database processing can be considerably reduced or eliminated by developing appropriate algo- rithms.