Add Throttling for Merges and Mutations in ClickHouse

Why it matters

This feature allows administrators to control and limit the bandwidth used by background merges and mutations to prevent resource overconsumption, improving cluster stability and performance by avoiding excessive disk or network usage during these operations.

How to use it

To use this feature, set the desired bandwidth limits (in bytes per second) via the server settings max_mutations_bandwidth_for_server and max_merges_bandwidth_for_server. For example, add to the server configuration file or use SET commands:

SET max_merges_bandwidth_for_server = 104857600; -- 100 MB/s
SET max_mutations_bandwidth_for_server = 52428800; -- 50 MB/s

These settings will throttle merges and mutations respectively across the server.