Prof. Dr. Felix Naumann

The Janus (IANVS) Project

Data change, all the time. In this project we want to explore and understand those changes. We call this activity change exploration:  For a given, dynamic dataset, we want to efficiently capture and summarize changes at instance-, and schema-level, enable users to effectively explore this change in an interactive and graphical fashion and analyze patterns in the changing data.


We choose a generic model to represent changes to a dataset. It includes the following four dimensions to represent what changed where, when, and how:

  1. Time
  2. Entity (ID)
  3. Property
  4. Value

A change c is a quadruple of the form

<Time, ID, Property, Value> or in brief <t, id, p, v>.

Its semantics is: At time t the property p of the entity identified with id was created as or changed to v.

A change-cube is a set of such changes.

For more details on our data model see our vision paper at ExploreDB'17.



  • Project lead: Prof. Felix Naumann
  • Doctoral researchers: Tobias Bleifuß and Leon Bornemann
  • Student assistant: Joana Bergsiek
  • In collaboration with: Theodore Johnson, Dmitri V. Kalashnikov, and Divesh Srivastava – AT&T Labs - Research


  • Bleifuß, Tobias, Leon Bornemann, Dmitri V. Kalashnikov, Felix Naumann, and Divesh Srivastava. DBChEx: Interactive Exploration of Data and Schema Change. In Proceedings of the Conference on Innovative Data Systems Research (CIDR), 2019.
  • Exploring Change - A New ... - Download
    Bleifuß, Tobias, Leon Bornemann, Theodore Johnson, Dmitri V. Kalashnikov, Felix Naumann, and Divesh Srivastava. Exploring Change - A New Dimension of Data Analytics. Proceedings of the VLDB Endowment (PVLDB). 12(2):85-98, 2018.
  • Bornemann, Leon, Tobias Bleifuß, Dmitri Kalashnikov, Felix Naumann, and Divesh Srivastava. Data Change Exploration using Time Series Clustering. Datenbank-Spektrum. 18(2):1-9, 2018. DOI:https://doi.org/10.1007/s13222-018-0285-x.
  • Enabling Change Explorati... - Download
    Bleifuß, Tobias, Theodore Johnson, Dmitri V. Kalashnikov, Felix Naumann, Vladislav Shkapenyuk, and Divesh Srivastava. Enabling Change Exploration (Vision). In Proceedings of the Fourth International Workshop on Exploratory Search in Databases and the Web (ExploreDB), pages 1-3, 2017.