Versioning in main-memory database systems from MusaeusDB to TarDISDB

As relational database systems do not support collaborative dataset editing, online lexicons—such as Wikipedia’s MediaWiki—build their own version control above the database system to allow constraint-preserving version checkouts or commits involving multiple tables. To eliminate the need for purpose-specific solutions, we propose adding version control as a layer on top of the database system or integrating versioning in the database system’s core. This paper presents the first two architectures for versioning an entire state of a database system with respect to references among multiple relations. We design the prototype MusaeusDB as a solution for existing database systems, either as an external tool or as an extended SQL interface. The prototype TardisDB—an extended main-memory database system—reuses multi-version concurrency control for in-place updates while keeping older versions accessible. For performance tests on different storage layouts, we create—based on Wikipedia’s page history—the TardisBenchmark. Our results show that it is indeed feasible to reduce wasted space while still ensuring constant retrieval time. Also, extending a main-memory database system’s multi-version concurrency control has no negative impact on the transactional throughput. For further research on database versioning, we offer a flexibly sized benchmark with time evolving, text-based datasets and compression techniques.