Implementing mapping composition

Mapping composition is a fundamental operation in metadata driven applications. Given a mapping over schemas 1 and 2 and a mapping over schemas 2 and 3, the composition problem is to compute an equivalent mapping over 1 and 3. We describe a new composition algorithm that targets practical applications. It incorporates view unfolding. It eliminates as many 2 symbols as possible, even if not all can be eliminated. It covers constraints expressed using arbitrary monotone relational operators and, to a lesser extent, non-monotone operators. And it introduces the new technique of left composition. We describe our implementation, explain how to extend it to support user-defined operators, and present experimental results which validate its effectiveness.

• Type: Conference
• Year: 2008
• Where: VLDB
• Authors: Philip A. Bernstein, Todd J. Green, Sergey Melnik, Alan Nash
• Keywords: Composition Problem, Database, Left Composition, Monotone Relational Operators, VLDB 2008