Semantic query processing in multidatabase systems: a logic-based approach

A multidatabase system (MDBS) is a system that integrates the operational data of several autonomous database systems and provides a uniform interface and control mechanisms to control access to those data. To efficiently retrieve and manipulate the data stored in MDBS, a metadata dictionary is needed as a repository of essential information for reasoning, controlling, and maintaining the retrieval/manipulation processes. The authors develop a two-level active metadata dictionary approach based on logic for building a metadata dictionary, query processing, and maintenance in MDBS. The low-level metadata dictionaries (LLMDs) keep metadata for each corresponding local database in MDBS, respectively. The high-level metadata dictionary (HLMD) integrates the metadata about all LLMDs