drop table if exists xy; create table xy(x int, y int) engine MergeTree partition by intHash64(x) % 2 order by y settings index_granularity = 1; -- intHash64(0) % 2 = 0 -- intHash64(2) % 2 = 1 -- intHash64(8) % 2 = 0 -- intHash64(9) % 2 = 1 insert into xy values (0, 2), (2, 3), (8, 4), (9, 5); -- Now we have two partitions: 0 and 1, each of which contains 2 values. -- minmax index for the first partition is 0 <= x <= 8 -- minmax index for the second partition is 2 <= x <= 9 SET max_rows_to_read = 2; select * from xy where intHash64(x) % 2 = intHash64(2) % 2; -- Equality is another special operator that can be treated as an always monotonic indicator for deterministic functions. -- minmax index is not enough. select * from xy where x = 8; drop table if exists xy; -- Test if we provide enough columns to generate a partition value drop table if exists xyz; create table xyz(x int, y int, z int) engine MergeTree partition by if(toUInt8(x), y, z) order by x settings index_granularity = 1; insert into xyz values (1, 2, 3); select * from xyz where y = 2; drop table if exists xyz; -- Test if we obey strict rules when facing NOT contitions drop table if exists test; create table test(d Date, k Int64, s String) Engine=MergeTree partition by (toYYYYMM(d),k) order by (d, k); insert into test values ('2020-01-01', 1, ''); insert into test values ('2020-01-02', 1, ''); select * from test where d != '2020-01-01'; drop table test; -- Test if single value partition pruning works correctly for Date = String drop table if exists myTable; CREATE TABLE myTable (myDay Date, myOrder Int32, someData String) ENGINE = ReplacingMergeTree PARTITION BY floor(toYYYYMMDD(myDay), -1) ORDER BY (myOrder); INSERT INTO myTable (myDay, myOrder) VALUES ('2021-01-01', 1); INSERT INTO myTable (myDay, myOrder) VALUES ('2021-01-02', 2); // This row should be returned INSERT INTO myTable (myDay, myOrder) VALUES ('2021-01-03', 3); SELECT * FROM myTable mt WHERE myDay = '2021-01-02'; drop table myTable;