DROP TABLE IF EXISTS mass_table_312; set allow_deprecated_syntax_for_merge_tree=1; CREATE TABLE mass_table_312 (d Date DEFAULT '2000-01-01', x UInt64, n Nested(a String, b String)) ENGINE = MergeTree(d, x, 1); INSERT INTO mass_table_312 SELECT * FROM generateRandom('`d` Date,`x` UInt64,`n.a` Array(String),`n.b` Array(String)', 1, 10, 2) LIMIT 100; SELECT count(), sum(cityHash64(*)) FROM mass_table_312; SELECT count(), sum(cityHash64(*)) FROM mass_table_312 ARRAY JOIN n; DROP TABLE mass_table_312;