H-Store was originally conceived as the academic prototype. The original version of H-Store was a single-node proof-of-concept used in the 2007 VLDB paper. In the beginning of 2008, researchers at Brown, MIT, and Yale started working on a full-fledged, general purpose H-Store system. At the same time, Horizontica was launched as an secret internal project at Vertica. Once again, these were separate code bases that were to serve separate purposes. In the spring of 2008, it was decided to merge together the backend execution engine of H-Store and the front-end transaction coordinator and query planner of Horizontica. After the VLDB demo in the fall of 2008, the H-Store codebase was forked off and became VoltDB. The final version was announced in 2016. There have been no new developments since then. The code
All transactions execute with `SERIALIZABLE` isolation. It is not possible to execute transactions at a lower isolation level.
All transactions are executed as Java-based stored procedures.
H-Store only supports simplistic views based on aggregations (e.g., `COUNT`, `SUM`).
Academic, Open Source
BSD, GPL v3