engine mt rmt create table alter_select_mt (part_id String, col_0 String) engine=MergeTree() partition by part_id order by tuple() settings max_parts_to_merge_at_once=1 create table alter_select_rmt (part_id String, col_0 String) engine=ReplicatedMergeTree('/tables/{{database}}', '{{table}}') partition by part_id order by tuple() settings max_parts_to_merge_at_once=1 system stop merges alter_select_{engine} insert into alter_select_{engine} (part_id, col_0) select toString(number % 5000), 0 from numbers(10000) settings max_block_size=1, max_insert_threads=32, min_insert_block_size_rows=1, insert_deduplicate=false, parts_to_delay_insert=100000, parts_to_throw_insert=100000 alter table alter_select_{engine} drop column col_0 settings alter_sync = 0 select count() from alter_select_{engine} format Null settings max_threads=1 select * from alter_select_{engine} format Null settings max_threads=1 drop table alter_select_{engine}