TardisDB: Extending SQL to Support Versioning

Abstract

Online encyclopaedias such as Wikipedia implement their own version control above database systems to manage multiple revisions of the same page. In contrast to temporal databases that restrict each tuple's validity to a time range, a version affects multiple tuples. To overcome the need for a separate version layer, we have created TardisDB, the first database system with incorporated data versioning across multiple relations. This paper presents the interface for TardisDB with an extended SQL to manage and query data from different branches. We first give an overview of TardisDB's architecture that includes an extended table scan operator: a branch bitmap indicates a tuple's affiliation to a branch and a chain of tuples tracks the different versions. This is the first database system that combines chains for multiversion concurrency control with a bitmap for each branch to enable versioning. Afterwards, we describe our proposed SQL extension to create, query and modify tables across different, named branches. In our demonstration setup, we allow users to interactively create and edit branches and display the lineage of each branch.