ClickHouse/docs/en/operations/system-tables/numbers.md

slug
/en/operations/system-tables/numbers

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.