Software systems evolve continuously during their lifecycle. Developers incrementally introduce new features and fix bugs during the process, leading to lots of changes and artifacts accumulated. Driven by those rich data recorded in version control systems or issue trackers, lots of work has been done to analyze the software histories. In this PhD work, we propose a universal representation to effectively store and query over knowledge extracted from the histories, with the hope of supporting software evolution research. We have created a toolset, named DIFF BASE , to extract both relations between program entities at the same version, as well as atomic changes between versions. Then users can compose queries using algebraic operators, Datalog or an SQL-like language to accomplish several different evolution management tasks. Based on the existing research outcome, possible future work includes utilizing the facts approach in a scalable solution to discovering compatibility issues involving changes of multiple components and improvement on the storage and query performance of DIFFBASE.