generateRandom Table Function

Generates random data with a given schema. Allows populating test tables with that data. Not all types are supported.

Arguments

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

Returned Value

A table object with requested schema.

Usage Example

In combination with generateRandomStructure:

With missing structure argument (in this case the structure is random):

With random seed both for random structure and random data:

Note: generateRandom(generateRandomStructure(), [random seed], max_string_length, max_array_length) with large enough max_array_length can generate really huge output due to possible big nesting depth (up to 16) of complex types (Array, Tuple, Map, Nested).

Related content

• Blog: Generating random data in ClickHouse