-- Tags: no-s3-storage, no-random-merge-tree-settings -- no-s3 because read FileOpen metric DROP TABLE IF EXISTS nested; SET flatten_nested = 0; SET use_uncompressed_cache = 0; SET local_filesystem_read_method='pread'; CREATE TABLE nested ( col1 Nested(a UInt32, s String), col2 Nested(a UInt32, n Nested(s String, b UInt32)), col3 Nested(n1 Nested(a UInt32, b UInt32), n2 Nested(s String, t String)) ) ENGINE = MergeTree ORDER BY tuple() SETTINGS min_bytes_for_wide_part = 0; INSERT INTO nested VALUES ([(1, 'q'), (2, 'w'), (3, 'e')], [(4, [('a', 5), ('s', 6), ('d', 7)])], [([(8, 9), (10, 11)], [('z', 'x'), ('c', 'v')])]); INSERT INTO nested VALUES ([(12, 'qq')], [(4, []), (5, [('b', 6), ('n', 7)])], [([], []), ([(44, 55), (66, 77)], [])]); OPTIMIZE TABLE nested FINAL; SELECT 'all'; SELECT * FROM nested; SELECT 'col1'; SELECT col1.a, col1.s FROM nested; SELECT 'col2'; SELECT col2.a, col2.n, col2.n.s, col2.n.b FROM nested; SELECT 'col3'; SELECT col3.n1, col3.n2, col3.n1.a, col3.n1.b, col3.n2.s, col3.n2.t FROM nested; SELECT 'read files'; SYSTEM DROP MARK CACHE; SELECT col1.a FROM nested FORMAT Null; -- 4 files: (col1.size0, col1.a) x2 SYSTEM FLUSH LOGS; SELECT ProfileEvents['FileOpen'] FROM system.query_log WHERE (type = 'QueryFinish') AND (lower(query) LIKE lower('SELECT col1.a FROM %nested%')) AND event_date >= yesterday() AND current_database = currentDatabase(); SYSTEM DROP MARK CACHE; SELECT col3.n2.s FROM nested FORMAT Null; -- 6 files: (col3.size0, col3.n2.size1, col3.n2.s) x2 SYSTEM FLUSH LOGS; SELECT ProfileEvents['FileOpen'] FROM system.query_log WHERE (type = 'QueryFinish') AND (lower(query) LIKE lower('SELECT col3.n2.s FROM %nested%')) AND event_date >= yesterday() AND current_database = currentDatabase(); DROP TABLE nested; CREATE TABLE nested ( id UInt32, col1 Nested(a UInt32, n Nested(s String, b UInt32)) ) ENGINE = MergeTree ORDER BY id SETTINGS min_bytes_for_wide_part = 0; INSERT INTO nested SELECT number, arrayMap(x -> (x, arrayMap(y -> (toString(y * x), y + x), range(number % 17))), range(number % 19)) FROM numbers(100000); SELECT id % 10, sum(length(col1)), sumArray(arrayMap(x -> length(x), col1.n.b)) FROM nested GROUP BY id % 10; SELECT arraySum(col1.a), arrayMap(x -> x * x * 2, col1.a) FROM nested ORDER BY id LIMIT 5; SELECT untuple(arrayJoin(arrayJoin(col1.n))) FROM nested ORDER BY id LIMIT 10 OFFSET 10; DROP TABLE nested;