DIG: Mm Serviço de Custos e Estatísticas para o Processamento Distribuído de Consultas

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