v.21.1Improvements

Cache Dictionaries: Eliminate Callbacks and Locks in Key Management

Cache dictionaries: Completely eliminate callbacks and locks for acquiring them. Keys are not divided into "not found" and "expired", but stored in the same map during query. #14958 (Nikita Mikhaylov).
Eliminate callbacks and locks for cache dictionaries by storing all keys in a single map during queries, without separating "not found" and "expired" keys.

Why it matters

This feature simplifies and optimizes cache dictionary access by removing the overhead caused by callbacks and locking mechanisms. By consolidating key storage, it improves performance and reduces complexity when querying cache dictionaries in ClickHouse.

How to use it

This improvement is applied internally in the cache dictionary implementation; users benefit automatically without needing to change configurations or query syntax.