Announcing ScyllaDB Open Source 5.1

ScyllaDB Open Source 5.1 introduces several enhancements and features aimed at improving the performance, stability, and capabilities of the NoSQL database. This minor release builds on the major 5.0 release, resolving over 100 issues and adding notable features like the distributed SELECT COUNT (*) with a new "super coordinator" role to optimize query speed across large clusters. It also introduces per-partition rate limits to manage read and write operations, helping to prevent hot partition issues. The Load and Stream feature facilitates easy data restoration without concern for original cluster topology, while the elimination of exceptions from the read and write paths enhances performance by reducing the overhead of timeout handling. The release also includes updates to the Raft consensus algorithm for improved schema management, a CQL extension to prune ghost rows from materialized views, and a new synchronous mode for materialized views to ensure consistency. Additionally, this version supports experimental features like Alternator TTL for data expiration in its DynamoDB-compatible API and WebAssembly-based user-defined functions and aggregates, providing a foundation for future enhancements.