v.21.3Improvement

Lockless SYSTEM FLUSH DISTRIBUTED Implementation

Lockless SYSTEM FLUSH DISTRIBUTED. #20215 (Azat Khuzhin).
Introduces a lockless implementation of SYSTEM FLUSH DISTRIBUTED command in ClickHouse.

Why it matters

This feature removes the need for locking when executing SYSTEM FLUSH DISTRIBUTED, thereby improving concurrency and reducing contention during distributed data flush operations. Users experience better performance and reduced wait times within their distributed ClickHouse clusters.

How to use it

Use the SYSTEM FLUSH DISTRIBUTED command as usual without any additional configuration. The lockless mechanism is applied internally to optimize the flush process.