ClickHouse/docs/en/sql-reference/table-functions/generate.md

slug	sidebar_position	sidebar_label
/en/sql-reference/table-functions/generate	47	generateRandom

generateRandom

Generates random data with given schema. Allows to populate test tables with data. Supports all data types that can be stored in table except LowCardinality and AggregateFunction.

generateRandom('name TypeName[, name TypeName]...', [, 'random_seed'[, 'max_string_length'[, 'max_array_length']]])

Arguments

• name — Name of corresponding column.
• TypeName — Type of corresponding column.
• max_array_length — Maximum array length for all generated arrays. Defaults to 10.
• max_string_length — Maximum string length for all generated strings. Defaults to 10.
• random_seed — Specify random seed manually to produce stable results. If NULL — seed is randomly generated.

Returned Value

A table object with requested schema.

Usage Example

SELECT * FROM generateRandom('a Array(Int8), d Decimal32(4), c Tuple(DateTime64(3), UUID)', 1, 10, 2) LIMIT 3;

┌─a────────┬────────────d─┬─c──────────────────────────────────────────────────────────────────┐
│ [77]     │ -124167.6723 │ ('2061-04-17 21:59:44.573','3f72f405-ec3e-13c8-44ca-66ef335f7835') │
│ [32,110] │ -141397.7312 │ ('1979-02-09 03:43:48.526','982486d1-5a5d-a308-e525-7bd8b80ffa73') │
│ [68]     │  -67417.0770 │ ('2080-03-12 14:17:31.269','110425e5-413f-10a6-05ba-fa6b3e929f15') │
└──────────┴──────────────┴────────────────────────────────────────────────────────────────────┘