max_delay_* MergeTree table settings

These settings are available in system.merge_tree_settings and are autogenerated from ClickHouse source.

max_delay_to_insert

The value in seconds, which is used to calculate the INSERT delay, if the number of active parts in a single partition exceeds the parts_to_delay_insert value.

Possible values:

• Any positive integer.

The delay (in milliseconds) for INSERT is calculated by the formula:

max_k = parts_to_throw_insert - parts_to_delay_insert
k = 1 + parts_count_in_partition - parts_to_delay_insert
delay_milliseconds = pow(max_delay_to_insert * 1000, k / max_k)

For example, if a partition has 299 active parts and parts_to_throw_insert = 300, parts_to_delay_insert = 150, max_delay_to_insert = 1, INSERT is delayed for pow( 1 * 1000, (1 + 299 - 150) / (300 - 150) ) = 1000 milliseconds.

Starting from version 23.1 formula has been changed to:

allowed_parts_over_threshold = parts_to_throw_insert - parts_to_delay_insert
parts_over_threshold = parts_count_in_partition - parts_to_delay_insert + 1
delay_milliseconds = max(min_delay_to_insert_ms, (max_delay_to_insert * 1000)
* parts_over_threshold / allowed_parts_over_threshold)

For example, if a partition has 224 active parts and parts_to_throw_insert = 300, parts_to_delay_insert = 150, max_delay_to_insert = 1, min_delay_to_insert_ms = 10, INSERT is delayed for max( 10, 1 * 1000 * (224 - 150 + 1) / (300 - 150) ) = 500 milliseconds.

max_delay_to_mutate_ms

Max delay of mutating MergeTree table in milliseconds, if there are a lot of unfinished mutations