MongoDB Atlas has introduced "Online Archive", a new paradigm for data tiering that allows users to seamlessly archive data across clusters and cloud object stores, enabling cost-effective storage and querying capabilities. With Online Archive, users can define archiving rules based on specific fields, choose commonly queried fields, and confirm archiving initiation. The feature is suitable for various use cases such as insert-only workloads, historical log keeping, time-series datasets, and storing data that would have been deleted using TTL indexes. After setting up an online archive, users can manage it, query live and archived data with a single connection string, and right-size their Atlas clusters by moving "cold" data to cheaper storage tiers.