Multilayered Database
Model and Approximate Query Processing Model for Mobile
Computing
In environments such as wireless computing, it is
neither practical nor necessary to adhere to provide
correct (i.e. sound and complete) answers for database
queries. Users may not obtain perfect answers to their
queries within an acceptable time and therefore, within
known limits of correctness and precision, an approximate
answer may suffice for some mobile users. Due to the
limited bandwidth, direct answering of queries from
a mobile device will likely jam the communication
and thus will be very slow. Therefore, it is better
to feed the information progressively as the client
refines the query. For examples, when a traveler drives
to a place, she uses her PDA to find about interesting
local attractions. To answer her query, the server
can first send a list of attractions with brief description
in text, and then send thumbnail images and directions
for some of the attractions, and eventually full size
images, maps, or video clips for the interested attractions.
Such practices of information filtering have been
done in an ad hoc way by many Web sites.
In this research, we proposed to create a generalized
multilayered systems where each layer can be generated
from the layer below using some generalization operators
such as Concept hierarchies (described later), sampling,
transformation, grouping etc. We have explored multi-layered
database and its potential and effectiveness in intelligent
query answering in mobile environments. A multi-layered
database (MLDB) is a database composed of several
layers of information, with the lowest layer corresponding
to the primitive information stored in a conventional
database, and with higher layers storing more general
information extracted from lower layers.
Resercher
Dr.
Sanjay Madria
Dr. Y. Fu, Nanyang Technological University, Singapore
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