Contemporary database research is concerned with the design of new programming languages to support advanced database applications such as software engineering information systems, office systems, and computer-aided design and manufacturing. Glue-Nail is a deductive database system that offers two complementary languages, one declarative and the other procedural, for writing such applications. This dissertation describes the design and implementation of IGlue, an interpreter for the Glue language. It focuses on the problem of query optimization: converting a declarative specification of a query into an efficient plan for executing the query.