UNIDAD ZACATENCO DEPARTAMENTO DE ... - Cinvestav

Abstract
One of the most important activities of distributed database design is partitioning, this
consists of dividing a relation or table into two or more relations (partitioning scheme)
which contain subsets of either tuples (horizontal partitioning), attributes (vertical par-
titioning), or tuples and attributes (hybrid fragmentation) to reduce both the number of
disk accesses and the remote data transported needed to answer a query, and in this way,
reducing the response time of such queries.
Vertical partitioning is a distributed database design technique widely employed in
traditional databases (relational and object-oriented databases that only manage numer-
ic and textual attributes) to reduce the number of irrelevant attributes accessed by the
queries. Currently, due to the popularity of multimedia applications on the Internet, the
need of using partitioning strategies in multimedia databases has arisen in order to use
their potential advantages with regard to query optimization. In multimedia databases,
the attributes tend to be of very large multimedia objects. Therefore, the reduction in the
number of accesses to objects which are not used by the queries (irrelevant) would imply
a considerable cost saving in the query execution.
Nevertheless, the use of vertical partitioning techniques in multimedia databases implies
two problems: 1) current vertical partitioning algorithms only take into account alphanu-
meric data, and 2) the partitioning process is carried out in a static way. In order to
solve these problems, we propose an active rule-based system (or active system) called DY-
MOND (DYnamic Multimedia ON line Distribution) which performs a dynamic vertical