ClickHouse has released its 21.12 Christmas version, which includes 2460 new commits and contributions from 125 contributors. The release highlights several key features, including support for "four letter commands" in ClickHouse Keeper, a feature complete replacement for ZooKeeper, improved partitions for INSERT INTO File, URL, and HDFS storages, enhanced glob patterns in FROM INFILE, improved INTERVAL operator support in the WITH FILL modifier for ORDER BY clause, added support for Identifier table and database query parameters, native boolean data type, query optimizations with table constraints, and read large remote files in chunks. These features aim to improve performance, simplify queries, and enhance security and compatibility with other databases.