Bidirectional Transformations in Database Evolution: A Case Study "At Scale"

Bidirectional transformations (BX) play an important role in database schema/application co-evolution. In earlier work, Terwilliger introduced the theoretical concept of a Channel as a BX-based mechanism to de-couple “virtual databases” used by the application code from the actual representation of the data maintained within the DBMS. In this paper, we report on considerations and experiences implementing such Channels in practice in the context of a complex real-world application, and with generative tool support. We focus on Channels implementing Pivot/Unpivot transformations. We present di↵erent alternatives for generating such Channels and discuss their performance characteristics at scale. We also present a transformational tool to generate these Channels.