Finding and Fixing Type Mismatches in the Evolution of Object-NoSQL Mappings.

NoSQL data stores are popular backends for managing big data that is evolving over time: Due to their schema-flexibility, a new release of the application does not require a full migration of data already persisted in production. Instead, using object-NoSQL mappers, developers can specify lazy data migrations that are executed on-the-fly, when a legacy entity is loaded into the application. This paper features ControVol, an IDE plugin that tracks evolutionary changes in object-NoSQL mappings, such as adding, renaming, or removing an attribute, which may conflict with entities already persisted in production. If not resolved prior to launch of the new application, harmful evolutionary changes can cause runtime exceptions or data loss. In this demo, we focus on a novel feature of ControVol, detecting changes to attribute types that are not backwards-compatible with legacy entities. When such changes occur, ControVol issues warnings, and upon the request of developers, assists in safely carrying out type changes.