ylfink@water.UUCP (ylfink) (02/11/86)
DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES
COMPUTER SCIENCE COLLOQUIUM
- Monday, February 17, 1986.
Dr. Timos Sellis of the University of California,
Berkeley will speak on ``Optimization of Extended Rela-
tional Database Systems''.
TIME: 3:30 PM
ROOM: MC 1050
ABSTRACT
In this talk I will examine some query processing
optimization problems that arise in an extended rela-
tional database management system. These extended
relational systems aim at increasing the functionality
of the existing systems in support of engineering and
AI applications. First, I will describe the prototype
environment, QUEL+ (extended QUEL), which motivates my
research. The two major enhancements of QUEL+ are *
storing relational expressions in relation fields, and
* repetitive execution of commands. The implications
that these extensions have on query processing are dis-
cussed 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 mul-
tiple command processing arises in the above context if
a field contains more than one query language expres-
sion that has to be evaluated. Optimization tactics
based on reordering the sequence of commands and on
transforming the sequence into a faster-executing but
semantically equivalent sequence of commands will be
presented. Finally, for processing collections of
retrieve-only commands, I will describe some multiple
query optimization algorithms that aim at reducing the
number of disk accesses.