RethinkDB is an open-source document-oriented database that enables real-time updates and easy sharding and replication. Datadog's RethinkDB integration provides granular visibility into the health and performance of your RethinkDB deployment, allowing you to monitor client activity, track scaling operations, ensure availability, and more. With this integration, users can customize dashboards, set automated alerts for server issues, and gain insights into how clients interact with their database cluster.