Abstract of Thesis presented to COPPE/UFRJ as a partial fulfillment
of the requirements for the degree of Master of Science (M.Sc.)

Department: Computer Science and Systems Engineering
Advisor: Marta Lima de Queirós Mattoso, D.Sc.

DIG: A SERVICE TO PROVIDE COSTS AND STATISTICS FOR DISTRIBUTED QUERY PROCESSING

Nicolaas Ruberg
November/2002

    Abstract. Cost parameters and database statistics are the basis of query optimization techniques. However, in distributed and heterogeneous database systems, acquiring and treating information to help the optimization process are often tasks of a global query processor, tailoring these functionalities to a specific system architecture. Moreover, this acquisition process involves a large number of parameters and requires customized methods to retrieve data from specific sources. DIG (Distributed Information Gatherer) is a cost and statistics provider that, through an independent and flexible service, aims to support global query optimization processing in distributed and heterogeneous database systems over autonomous data sources. We developed a DIG prototype and evaluated it with specific wrappers for a query middleware on semi-structured data sources and also for an ORDBMS.

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Updated February, 2003