uniqHLL12 vs uniqTheta

uniqHLL12_vs_uniqTheta

create table x (a Int64, b Int64, c Int64, 
 u AggregateFunction(uniqHLL12, String), 
 t AggregateFunction(uniqTheta, String)) 
Engine=MergeTree order by (a,b,c);

insert into x select number%11111 a, number%44 b, number%3 c, uniqHLL12State(number::String), uniqThetaState(number::String)
from numbers(1e7) group by a,b,c;

optimize table x final;

select a, b, uniqHLL12Merge(u) from x group by a, b format Null;
0 rows in set. Elapsed: 0.348 sec. Processed 1.47 million rows, 258.13 MB (4.21 million rows/s., 741.63 MB/s.)
Peak memory usage: 1.57 GiB.

select a, b, uniqThetaMerge(t) from x group by a, b format Null;
0 rows in set. Elapsed: 0.848 sec. Processed 1.47 million rows, 58.67 MB (1.73 million rows/s., 69.17 MB/s.)
Peak memory usage: 645.29 MiB.


select uniqHLL12Merge(u) from x;
┌─uniqHLL12Merge(u)─┐
│           9915063 │
└───────────────────┘
1 row in set. Elapsed: 0.105 sec. Processed 1.47 million rows, 234.66 MB (13.95 million rows/s., 2.23 GB/s.)
Peak memory usage: 21.33 MiB.


select uniqThetaMerge(t) from x;
┌─uniqThetaMerge(t)─┐
│           9943597 │
└───────────────────┘
1 row in set. Elapsed: 0.572 sec. Processed 1.47 million rows, 35.20 MB (2.56 million rows/s., 61.53 MB/s.)
Peak memory usage: 177.87 MiB.