diff --git a/docs/en/operations/settings/settings.md b/docs/en/operations/settings/settings.md index 19db4be17db..3617e6a3167 100644 --- a/docs/en/operations/settings/settings.md +++ b/docs/en/operations/settings/settings.md @@ -2855,7 +2855,7 @@ The minimum chunk size in bytes, which each thread will parse in parallel. ## merge_selecting_sleep_ms {#merge_selecting_sleep_ms} -Sleep time for merge selecting when no part is selected. A lower setting triggers selecting tasks in `background_schedule_pool` frequently, which results in a large number of requests to ClickHouse Keeper in large-scale clusters. +Minimum sleep time for merge selecting when no part is selected. A lower setting triggers selecting tasks in `background_schedule_pool` frequently, which results in a large number of requests to ClickHouse Keeper in large-scale clusters. Possible values: @@ -2863,6 +2863,16 @@ Possible values: Default value: `5000`. +## max_merge_selecting_sleep_ms + +Maximum sleep time for merge selecting when no part is selected. A lower setting triggers selecting tasks in `background_schedule_pool` frequently, which results in a large number of requests to ClickHouse Keeper in large-scale clusters. + +Possible values: + +- Any positive integer. + +Default value: `60000`. + ## parallel_distributed_insert_select {#parallel_distributed_insert_select} Enables parallel distributed `INSERT ... SELECT` query. diff --git a/src/Storages/MergeTree/MergeTreeSettings.h b/src/Storages/MergeTree/MergeTreeSettings.h index de1f0f60cfc..676f776df54 100644 --- a/src/Storages/MergeTree/MergeTreeSettings.h +++ b/src/Storages/MergeTree/MergeTreeSettings.h @@ -67,7 +67,7 @@ struct Settings; M(Bool, fsync_part_directory, false, "Do fsync for part directory after all part operations (writes, renames, etc.).", 0) \ M(UInt64, non_replicated_deduplication_window, 0, "How many last blocks of hashes should be kept on disk (0 - disabled).", 0) \ M(UInt64, max_parts_to_merge_at_once, 100, "Max amount of parts which can be merged at once (0 - disabled). Doesn't affect OPTIMIZE FINAL query.", 0) \ - M(UInt64, merge_selecting_sleep_ms, 5000, "Maximum sleep time for merge selecting, 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", 0) \ + M(UInt64, merge_selecting_sleep_ms, 5000, "Minimum sleep time for merge selecting, 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", 0) \ M(UInt64, max_merge_selecting_sleep_ms, 60000, "Maximum sleep time for merge selecting, 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", 0) \ M(Float, merge_selecting_sleep_slowdown_factor, 1.2f, "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", 0) \ M(UInt64, merge_tree_clear_old_temporary_directories_interval_seconds, 60, "The period of executing the clear old temporary directories operation in background.", 0) \