ClickHouse/docs/en/query_language/table_functions/generate.md

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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']]]);

Parameters

  • name — Name of corresponding column.
  • TypeName — Type of corresponding column.
  • limit — Number of rows to generate.
  • 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);
┌─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') │
└──────────┴──────────────┴────────────────────────────────────────────────────────────────────┘

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