These settings are available in system.merge_tree_settings and are autogenerated from the ClickHouse snapshot.
merge_selecting_sleep_ms
Minimum time to wait before trying to select parts to merge again after no parts were selected. A lower setting will trigger selecting tasks in background_schedule_pool frequently which result in large amount of requests to zookeeper in large-scale clusters
merge_selecting_sleep_slowdown_factor
The sleep time for merge selecting task is multiplied by this factor when there’s nothing to merge and divided when a merge was assigned