clarke@utcsri.UUCP (Jim Clarke) (02/03/86)
(RS = Rosebrugh Building, Taddlecreek Road (GB = Galbraith Building, 35 St. George Street) (SF = Sandford Fleming Building, 10 King's College Rd.) SYSTEMS SEMINAR, Friday, Feb. 7, 11 am, RS 211 Professor Sam Toueg Cornell University To be announced SYSTEMS/THEORY SEMINAR, Monday, Feb.10, 3 pm, SF3202 Doug Tygar Harvard University "An Integrated Toolkit for Operating System Security" (joint work with Michael Rabin) SYSTEMS SEMINAR, Thursday, Feb.13, 11 am, GB 220 Timos Sellis University of California, Berkeley "Optimization of Extended Relational Database Management Systems" In this talk I will examine some query processing optimization prob- lems that arise in an extended relational database management system. First, I will describe the prototype environment, QUEL+ (extended QUEL), which motivates my research. The two major enhancements of QUEL+ are (i) storing relational expressions in relation fields, and (ii) repetitive exe- cution of commands. The implications that these extensions have on query processing are discussed and some conventional query optimization tactics are proposed for this extended language. Then, I will elaborate on the problem of optimizing a collection of commands rather than one command at a time. Such multiple command processing arises in the above context if a field contains more than one query language expression that has to be evaluated. Optimization tactics based on reordering the sequence of com- mands and on transforming the sequence into a faster-executing but semanti- cally equivalent sequence of commands will be presented. Finally, for pro- cessing collections of retrieve-only commands, I will describe some multi- ple query optimization algorithms that aim at reducing the number of disk accesses. PLEASE NOTE The following talk has been arranged by University College as part of the Lectures in Peace Studies. Professor David Parnas Computer Science, University of Victoria Why the Strategic Defense Initiative Can Never Be Trusted Wednesday, 5 February 1986, 8 pm West Hall, University College, University of Toronto. -- Jim Clarke -- Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4 (416) 978-4058 {allegra,cornell,decvax,ihnp4,linus,utzoo}!utcsri!clarke