Managing Structurally Heterogeneous Databases in Software Product Lines

Abstract

Data variations are prevalent while developing software product lines (SPLs). A SPL enables a software vendor to quickly produce different variants of their software tailored to variations in their clients’ business requirements, conventions, desired feature sets, and deployment environments. In database-backed software, the database of each variant may have a different schema and content, giving rise to numerous data variants. Users often need to query and/or analyze all variants in a SPL simultaneously. For example, a software vendor wants to perform common tests or inquiries over all variants. Unfortunately, there is no systematic approach to managing and querying data variations and users have to use their intuition to perform such tasks, often resorting to repeating a task for each variant. We introduce VDBMS (Variational Database Management System), a system that provides a compact, expressive, and structured representation of variation in relational databases. In contrast to data integration systems that provide a unified representation for all data sources, VDBMS makes variations explicit in both the schema and query. Although variations can make VDBMS queries more complex than plain queries, a strong static type system ensures that all variants of the query are consistent with the corresponding variants of the database. Additionally, variational queries make it possible to compactly represent and efficiently run queries over a huge range of data variations in a single query. This directly supports many tasks that would otherwise be intractable in highly variational database-backed SPLs.