What sets RisingWave apart is its focus on stream processing while maintaining SQL compatibility. This could be particularly valuable for users leveraging Rockset's real-time capabilities. RisingWave offers several features that may appeal to Rockset users. It's built to scale in cloud environments and can ingest data from a large variety of sources. The database supports materialized views for efficient query processing and ensures data consistency with ACID transactions. For those concerned about vendor lock-in after this experience, RisingWave's open-source nature (Apache 2.0 license) provides an extra layer of assurance. There's also a managed cloud offering for those who prefer a hands-off approach.
I encourage impacted Rockset users to explore RisingWave as part of their evaluation process. The project has a welcoming community(join at risingwave.com/slack) and extensive documentation to help with the transition. [Disclosure: I'm associated with RisingWave. Happy to answer any questions or provide more details about how it compares to Rockset for specific use cases.]