-- { echo }

DROP TABLE IF EXISTS t_sparse;
DROP TABLE IF EXISTS t_sparse_1;
CREATE TABLE t_sparse (id UInt64, u UInt64, s String, arr1 Array(String), arr2 Array(UInt64))
ENGINE = MergeTree ORDER BY tuple()
SETTINGS ratio_of_defaults_for_sparse_serialization = 0.1;
INSERT INTO t_sparse SELECT
    number,
    if (number % 10 = 0, number, 0),
    if (number % 5 = 0, toString(number), ''),
    if (number % 7 = 0, arrayMap(x -> toString(x), range(number % 10)), []),
    if (number % 12 = 0, range(number % 10), [])
FROM numbers (200);
SELECT column, serialization_kind FROM system.parts_columns
WHERE table = 't_sparse' AND database = currentDatabase()
ORDER BY column;
arr1	Default
arr2	Default
id	Default
s	Sparse
u	Sparse
SELECT * FROM t_sparse WHERE u != 0 ORDER BY id;
10	10	10	[]	[]
20	20	20	[]	[]
30	30	30	[]	[]
40	40	40	[]	[]
50	50	50	[]	[]
60	60	60	[]	[]
70	70	70	[]	[]
80	80	80	[]	[]
90	90	90	[]	[]
100	100	100	[]	[]
110	110	110	[]	[]
120	120	120	[]	[]
130	130	130	[]	[]
140	140	140	[]	[]
150	150	150	[]	[]
160	160	160	[]	[]
170	170	170	[]	[]
180	180	180	[]	[]
190	190	190	[]	[]
SELECT * FROM t_sparse WHERE s != '' ORDER BY id;
0	0	0	[]	[]
5	0	5	[]	[]
10	10	10	[]	[]
15	0	15	[]	[]
20	20	20	[]	[]
25	0	25	[]	[]
30	30	30	[]	[]
35	0	35	['0','1','2','3','4']	[]
40	40	40	[]	[]
45	0	45	[]	[]
50	50	50	[]	[]
55	0	55	[]	[]
60	60	60	[]	[]
65	0	65	[]	[]
70	70	70	[]	[]
75	0	75	[]	[]
80	80	80	[]	[]
85	0	85	[]	[]
90	90	90	[]	[]
95	0	95	[]	[]
100	100	100	[]	[]
105	0	105	['0','1','2','3','4']	[]
110	110	110	[]	[]
115	0	115	[]	[]
120	120	120	[]	[]
125	0	125	[]	[]
130	130	130	[]	[]
135	0	135	[]	[]
140	140	140	[]	[]
145	0	145	[]	[]
150	150	150	[]	[]
155	0	155	[]	[]
160	160	160	[]	[]
165	0	165	[]	[]
170	170	170	[]	[]
175	0	175	['0','1','2','3','4']	[]
180	180	180	[]	[]
185	0	185	[]	[]
190	190	190	[]	[]
195	0	195	[]	[]
SELECT * FROM t_sparse WHERE arr1 != [] ORDER BY id;
7	0		['0','1','2','3','4','5','6']	[]
14	0		['0','1','2','3']	[]
21	0		['0']	[]
28	0		['0','1','2','3','4','5','6','7']	[]
35	0	35	['0','1','2','3','4']	[]
42	0		['0','1']	[]
49	0		['0','1','2','3','4','5','6','7','8']	[]
56	0		['0','1','2','3','4','5']	[]
63	0		['0','1','2']	[]
77	0		['0','1','2','3','4','5','6']	[]
84	0		['0','1','2','3']	[0,1,2,3]
91	0		['0']	[]
98	0		['0','1','2','3','4','5','6','7']	[]
105	0	105	['0','1','2','3','4']	[]
112	0		['0','1']	[]
119	0		['0','1','2','3','4','5','6','7','8']	[]
126	0		['0','1','2','3','4','5']	[]
133	0		['0','1','2']	[]
147	0		['0','1','2','3','4','5','6']	[]
154	0		['0','1','2','3']	[]
161	0		['0']	[]
168	0		['0','1','2','3','4','5','6','7']	[0,1,2,3,4,5,6,7]
175	0	175	['0','1','2','3','4']	[]
182	0		['0','1']	[]
189	0		['0','1','2','3','4','5','6','7','8']	[]
196	0		['0','1','2','3','4','5']	[]
SELECT * FROM t_sparse WHERE arr2 != [] ORDER BY id;
12	0		[]	[0,1]
24	0		[]	[0,1,2,3]
36	0		[]	[0,1,2,3,4,5]
48	0		[]	[0,1,2,3,4,5,6,7]
72	0		[]	[0,1]
84	0		['0','1','2','3']	[0,1,2,3]
96	0		[]	[0,1,2,3,4,5]
108	0		[]	[0,1,2,3,4,5,6,7]
132	0		[]	[0,1]
144	0		[]	[0,1,2,3]
156	0		[]	[0,1,2,3,4,5]
168	0		['0','1','2','3','4','5','6','7']	[0,1,2,3,4,5,6,7]
192	0		[]	[0,1]
SELECT sum(u) FROM t_sparse;
1900
SELECT sum(u) FROM t_sparse GROUP BY id % 7;
210
360
300
240
190
330
270
SELECT arrayFilter(x -> x % 2 = 1, arr2) FROM t_sparse WHERE arr2 != [] LIMIT 5;
[1]
[1,3]
[1,3,5]
[1,3,5,7]
[1]
CREATE TABLE t_sparse_1 (id UInt64, v Int64)
ENGINE = MergeTree ORDER BY tuple()
SETTINGS ratio_of_defaults_for_sparse_serialization = 0;
INSERT INTO t_sparse_1 VALUES (1, 6), (2, 1), (3, 0), (4, -1), (5, 0), (6, 0), (7, -2), (8, 0), (9, 0), (10, 4), (11, 0);
SELECT * FROM t_sparse_1 ORDER BY v, id;
7	-2
4	-1
3	0
5	0
6	0
8	0
9	0
11	0
2	1
10	4
1	6
SELECT * FROM t_sparse_1 ORDER BY v DESC, id;
1	6
10	4
2	1
3	0
5	0
6	0
8	0
9	0
11	0
4	-1
7	-2
SELECT * FROM t_sparse_1 ORDER BY v, id LIMIT 5;
7	-2
4	-1
3	0
5	0
6	0
SELECT * FROM t_sparse_1 ORDER BY v DESC, id LIMIT 5;
1	6
10	4
2	1
3	0
5	0
DROP TABLE t_sparse;
DROP TABLE t_sparse_1;