Extending JSON CRDTs with Move Operations

TL;DR

This paper presents a new algorithm for move operations in JSON CRDTs that manages concurrent updates effectively and improves performance, addressing challenges like duplicates and cycles during subtree moves.

Contribution

The paper introduces a novel move operation algorithm for JSON CRDTs that handles concurrency and optimizes performance, enhancing existing CRDT capabilities.

Findings

Algorithm effectively manages concurrent move and non-move operations.

Reduces issues like duplicates and cycles during subtree moves.

Plans integration into Automerge CRDT library.

Abstract

Conflict-Free Replicated Data Types (CRDTs) for JSON allow users to concurrently update a JSON document and automatically merge the updates into a consistent state. Moving a subtree in a map or reordering elements in a list within a JSON CRDT is challenging: naive merge algorithms may introduce unexpected results such as duplicates or cycles. In this paper, we introduce an algorithm for move operations in a JSON CRDT that handles the interaction with concurrent non-move operations, and uses novel optimisations to improve performance. We plan to integrate this algorithm into the Automerge CRDT library.