Eventually-Consistent Replicated Relations and Updatable Views

Abstract

Distributed systems have to live with weak consistency, such as eventual consistency, if high availability is the primary goal and network partitioning is unexceptional. Local-first applications are examples of such systems. There is currently work on local-first databases where the data are asynchronously replicated on multiple devices and the replicas can be locally updated even when the devices are offline. Sometimes, a user may want to maintain locally a copy of a view instead of the entire database. For the view to be fully useful, the user should be able to both query and update the local copy of the view. We present an approach to maintaining updatable views where both the source database and the views are asynchronously replicated. The approach is based on CRDTs (Conflict-free Replicated Data Types) and guarantees eventual consistency.