1 CREATE TABLE t_json (data JSON) ENGINE = MergeTree ORDER BY tuple() SETTINGS min_rows_for_wide_part=1000000000, min_bytes_for_wide_part=100000000000 INSERT INTO t_json SELECT toJSONString(map(number % 10, repeat('a', number % 100))) FROM numbers(10000000) SELECT data.k0, data.k1, data.k2, data.k3, data.k4, data.k5, data.k6, data.k7, data.k8, data.k9 FROM t_json FORMAT Null DROP TABLE IF EXISTS t_json