1 CREATE TABLE array_data(k UInt16, v Array(UInt64)) ENGINE Log INSERT INTO array_data SELECT number % 1024, arrayWithConstant(16, number) from numbers(10000000) SELECT countMerge(v) FROM (SELECT countState() v FROM zeros(1000000000)) FORMAT Null SELECT countMerge(v) FROM (SELECT number % 1024 k, countState() v FROM numbers(10000000) GROUP BY k) FORMAT Null SELECT sumArray(v) FROM array_data FORMAT Null SELECT k, sumArray(v) FROM array_data GROUP BY k FORMAT Null SELECT arrayReduce('avg', v) FROM array_data FORMAT Null DROP TABLE IF EXISTS array_data