Multidatabase Query Processing
In the previous three chapters, we have considered query processing in tighly-coupled homogeneous distributed database systems. As we discussed in Chapter 1, these systems are logically integrated and provide a single image of the database, even though they are physically distributed. In this chapter, we concentrate on query processing in multidatabase systems that provide interoperability among a set of DBMSs. This is only one part of the more general interoperability problem. Distributed applications pose major requirements regarding the databases they access, in particular, the ability to access legacy data as well as newly developed databases. Thus, providing integrated access to multiple, distributed databases and other heterogeneous data sources has become a topic of increasing interest and focus.
KeywordsQuery Processing Query Optimization Query Execution Conjunctive Query Global Relation
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