To achieve maximum performance, analytical databases optimize every step of their internal data storage and processing pipeline. ClickHouse uses caching extensively to avoid unnecessary work by storing the results of earlier computation or remote data, which is expensive to access. The Query Cache in ClickHouse is a new feature that caches the result of expensive SELECT queries, reducing latency and resource consumption. It stores query results based on their Abstract Syntax Tree (AST) instead of query text, making caching agnostic to upper and lowercase changes. The cache uses a default time-to-live (TTL) of 60 seconds for query results, but this can be specified using the `query_cache_ttl` setting. To enable caching for a query, run it with the `use_query_cache` setting. The Query Cache is transactionally inconsistent by design, tolerating slightly inaccurate query results and avoiding scalability issues that plagued MySQL's query cache. Future improvements include more sophisticated eviction strategies, compression of cache entries, paging on disk, caching of subqueries, and additional configuration settings.