Possibility to Distribute Merges Across Replicas with New Setting

Why it matters

This feature addresses the problem of merge operations overloading a single replica by enabling the distribution of merges across multiple replicas. It improves cluster resource utilization and reduces replication lag by balancing merge workloads more evenly.

How to use it

Users can enable this feature by setting execute_merges_on_single_replica_time_threshold in their MergeTree table settings or server configuration files. Adjusting this threshold controls when merges start being distributed among replicas.