Another funny idea to investigate: Single ClickHouse server can't have 2 queries with the same query id... In first shell: > clickhouse-client --query "SELECT sleepEachRow(3) FROM system.zeros FORMAT Null SETTINGS max_block_size=1" --query_id 2 --send_timeout 1 In second shell: > clickhouse-client --query "SELECT sleepEachRow(3) FROM system.zeros FORMAT Null SETTINGS max_block_size=1" --query_id 2 --send_timeout 1 Received exception from server (version 22.10.1): Code: 216. DB::Exception: Received from localhost:9000. DB::Exception: Query with id = 2 is already running.. (QUERY_WITH_SAME_ID_IS_ALREADY_RUNNING) ( query : SELECT sleepEachRow( 3 ) FROM system.zeros FORMAT Null SETTINGS max_block_size= 1 )