CH-skip-index

CH-skip-index

create table BX(I Int64, S String) Engine=MergeTree order by I;
insert into BX select number, toString(rand()) from numbers(10000000);
ALTER TABLE  BX ADD INDEX idx0 S TYPE minmax GRANULARITY 10;
optimize table BX final;

select count() from BX prewhere S = '666';
0 rows in set. Processed 10.00 million rows,

select count() from BX prewhere S = 'A';
0 rows in set. Elapsed: 0.001 sec.

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CREATE TABLE X
(  u64 UInt64,
   t UInt64,
   INDEX z t TYPE minmax GRANULARITY 3
)
ENGINE = MergeTree() ORDER BY u64

insert into X select number,number from numbers(1000000000);

select * from X where t=1000;
1 rows in set. Elapsed: 0.011 sec. Processed 24.58 thousand rows,

select * from X where t+0=1000;
1 rows in set. Elapsed: 6.482 sec. Processed 1.00 billion rows