Query transformation techniques for interoperable query processing in cooperative information systems
Louiqa Raschid, Ya‐Hui Chang, Bonnie Jean Dorr · 1994
: This paper describes a technique to support interoperable query processing, when multiple heterogeneous servers are accessed in a cooperative information system (CoopIS). The problem is to support query transformation transparently, so a user can pose queries locally, without needing global knowledge about different data models and schema in the CoopIS. An architecture for supporting interoperability is described and we provide some details of transforming queries from an object schema to an equivalent relational schema. We describe some functional modules, in detail, namely an extractor module (EM) which extracts semantics from a source query, and a heterogeneous mapping module (HTM) which maps among entities in different schema, based on some mapping rules which reflect global knowledge of the models, schema and query languages. The local and global dictionary knowledge is represented in a canonical form, using a high-level logic representation, namely F-logic. 1 Thi...