Scherzinger, StefanieKlettke, MeikeStörl, UtaSeidl, ThomasRitter, NorbertSchöning, HaraldSattler, Kai-UweHärder, TheoFriedrich, SteffenWingerath, Wolfram2017-06-302017-06-302015978-3-88579-635-0Schema-less NoSQL data stores offer great flexibility in application development, particularly in the early stages of software design. Yet over time, software engineers struggle with the heavy burden of dealing with increasingly heterogeneous data. In this demo we present Cleager, a framework for eagerly managing schema evolution in schema-less NoSQL document stores. Cleager executes declarative schema modification operations as MapReduce jobs on the Google Cloud Platform. We present different scenarios that require data migration, such as adding, removing, or renaming properties of persisted objects, as well as copying and moving them between objects. Our audience can declare the required schema migration operations in the Cleager console, and then verify the results in real time.enText/Conference Paper1617-5468