Relational Database ManagementSystems : Harmonizing SQL and SGMLG

Combined text and relational database support is increasingly recognized as an emerging need of industry, spanning applications requiring text elds as parts of their data (e.g., for customer support) to those augmenting primary text resources by conventional relational data (e.g., for publication control). In this paper, we propose extensions to SQL that provide exible and eecient access to structured text described by SGML. We also propose an architecture to support a text/relational database management system as a federated database environment , where component databases are accessed via \agents": SQL agents that translate standard or extended SQL queries into vendor-speciic dialects, and text agents that process text sub-queries on full-text search engines.