DROP TABLE IF EXISTS table_for_alter; CREATE TABLE table_for_alter ( id UInt64, Data String ) ENGINE = MergeTree() ORDER BY id SETTINGS parts_to_throw_insert = 1, parts_to_delay_insert = 1; INSERT INTO table_for_alter VALUES (1, '1'); INSERT INTO table_for_alter VALUES (2, '2'); -- { serverError 252 } INSERT INTO table_for_alter settings parts_to_throw_insert = 100, parts_to_delay_insert = 100 VALUES (2, '2'); INSERT INTO table_for_alter VALUES (3, '3'); -- { serverError 252 } ALTER TABLE table_for_alter MODIFY SETTING parts_to_throw_insert = 100, parts_to_delay_insert = 100; INSERT INTO table_for_alter VALUES (3, '3');