numbers
This table contains a single UInt64 column named number that contains almost all the natural numbers starting from zero.
You can use this table for tests, or if you need to do a brute force search.
Reads from this table are not parallelized.
Example
SELECT * FROM system.numbers LIMIT 10;
┌─number─┐
│      0 │
│      1 │
│      2 │
│      3 │
│      4 │
│      5 │
│      6 │
│      7 │
│      8 │
│      9 │
└────────┘
10 rows in set. Elapsed: 0.001 sec.
You can also limit the output by predicates.
SELECT * FROM system.numbers < 10;
┌─number─┐
│      0 │
│      1 │
│      2 │
│      3 │
│      4 │
│      5 │
│      6 │
│      7 │
│      8 │
│      9 │
└────────┘
10 rows in set. Elapsed: 0.001 sec.