Abstract
With the cutting edge technology advance in wireless and mobile computers, the query
processing in a mobile environment involves join processing among different sites which
include static servers and mobile computers. Because of the need for energy saving and also
the presence of asymmetric features in a mobile computing environment, the conventional
query processing for a distributed database cannot be directly applied to a mobile computing
system.
the regular optimization algorithms of distributed query, such as the optimization
algorithm based on join,the optimization algorithm based on semi join,SDD-1 algorithm,
have been greatly researched and widly used in DDBMS. Mobile DBMS is one kind of
DDBMS which supports mobile computing. However, the regular optimization algorithms
used in DDBMS must be developed so as to apple to the Mobile DBMS. without doing any
changes, these algorithms won’t be fitted for the mobile computing environment.
There are many asymmetric features in a mobile environment. Then, in light of these
features, query processing methods for both join and query processing can be devised.
Intuitively, employing semijoin operations in a mobile computing environment is able to
further reduce both the amount of data transmission and energy consumption. According to
those asymmetric features of a mobile computing system, two different join methods have
been examined. For query processing, which refers to the processing of multijoin queries,
two query processing schemes are devised.
It is shown by the simulation results that, by exploiting the asymmetric features, these
characteristic functions are very powerful in reducing both the amounts of energy
consumption and data transmission incurred and can lead to the design of an efficient and
effective query processing procedure for a mobile computing environment.
Key words: mobile computing, query processing, join method, multijoin queries.
