|PODS '97 -- ACM
on Principles of Database Systems
The sixteenth edition of the ACM
Symposium on Principles of Database Systems (PODS) was held in Tucson, Arizona, May 12-14,
1997. As it has been the case for each of the past six years, the PODS
conference was held in conjunction with the ACM International Conference on Management of
Data (SIGMOD), to foster close collaboration between the theoretical and applied database
research communities. The two conferences had separate program committees and separate
proceedings: theoretical papers contributed to PODS and applied ones to SIGMOD. However,
there was only one registration process for the joint conference, and attendees received
both proceedings and were free to attend sessions in both conferences. Moreover, some of
the technical events, the lunches, and the outing were joint events. Overall, there were
more than 500 registrants, and attendance in the sessions was always high, even when
parallel events was occurring.
PODS'97 program featured one invited
talk, three invited tutorials, and 23 contributed papers.
In his invited talk, Avi Silberschatz
provided an overview on the support for multimedia data (images, video, audio) provided by
next generation database systems, and highlighted the main challenges in
devising new algorithms to manage this new type of data. He first discussed the need for
support in database systems and the problem of specifying and evaluating content-based
queries. Then, he presented different approaches related to the storage and retrieval of
All three tutorials featured
challenging topics in the database research area.
In the first tutorial, Richard Hull
discussed fundamental problems raised by semantic heterogeneity in
databases, and presented a broad overview of theoretical frameworks that can provide
solutions for them. He started by the assumption that "data modeling is an art'', and
so "theoretical frameworks can help the humans, but not replace them''. He then
examined three main issues: the problem of schema restructuring, with an emphasis on
comparing the information capacity of different schemes; the problem of schema merging,
illustrating, among others, an approach based on description logic; and the use of
different paradigms for integrating data, according to a "closed world assumption''
or an "open world assumption''.
The tutorial of Peter Buneman covered a
number of issues related to the management of "semistructured'' data, for which there
is not a clear scheme describing them. The most immediate example of semistructured data
is the information coming from the Web. He first illustrated a flexible model and a
language for semistructured data, and then addressed, in this framework, the important
topics of implementation and optimization.
In the third tutorial, Arie Shoshani
compared the research done on statistical databases, with the
emerging research area of On-Line Analytical Processing (OLAP) for the analysis of
business data. He first pointed out the similarities between the two areas and the
correspondence between terminologies. He then identified which research aspects are
emphasized in each of these areas and illustrated important results in both of them. He
concluded by arguing that the work done in one area can greatly benefit the other.
The 23 contributed papers were selected
out of 118 submissions by a program committee chaired by Meral Ozsoyoglu. There were
sessions on various topics: database queries, spatial databases, logic and databases, web
and graph queries, replicated and continuous data, new databse applications, and query
processing and optimization.
A rather significant number of papers
considered various logic-based aspects: complexity of database queries (paper by
Papadimitriou and Yannakakis), containment of queries (papers by Levy and Suciu, by Ibarra
and Su, and by Albert and Ioannidis), query languages over interpreted structures (paper
by Benedikt and Libkin), answering queries using views (papers by Beeri, Levy, and
Rousset, and by Duschka and Genesereth) queries over paths (paper by Abiteboul and Vianu),
queries over the Web (papers by Mendelzon and Milo, and by Atzeni and Mecca), and logic
rules for referential actions (paper by Ludascher, May and Lausen).
Finally, the program committee granted
two new PODS awards: the Best Paper Award, and the Best Newcomer Paper Award. The PODS'97
Best Paper Award was awarded to Christos Papadimitriou and Mihalis Yannakakis for their
paper on the complexity of database queries, in which they revisit the issue of query
complexity in the light of the recent parametric refinement of complexity theory. The
PODS'97 Best Newcomer Paper Award was awarded to Oliver Duschka and Michael Genesereth for
their paper on answering recursive queries using views, in which they extend previous
results over conjunctive queries to general recursive queries.
Dipartimento di Informatica e
Universita di Roma Tre
Via della Vasca Navale 79
00146 Roma, Italy