ClickHouse/docs/en/engines/table-engines/special/generate.md

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---
toc_priority: 46
toc_title: GenerateRandom
---
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# GenerateRandom Table Engine {#table_engines-generate}
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The GenerateRandom table engine produces random data for given table schema.
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Usage examples:
- Use in test to populate reproducible large table.
- Generate random input for fuzzing tests.
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## Usage in ClickHouse Server {#usage-in-clickhouse-server}
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``` sql
ENGINE = GenerateRandom(random_seed, max_string_length, max_array_length)
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```
The `max_array_length` and `max_string_length` parameters specify maximum length of all
array columns and strings correspondingly in generated data.
Generate table engine supports only `SELECT` queries.
It supports all [DataTypes](../../../sql-reference/data-types/index.md) that can be stored in a table except `LowCardinality` and `AggregateFunction`.
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## Example {#example}
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**1.** Set up the `generate_engine_table` table:
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``` sql
CREATE TABLE generate_engine_table (name String, value UInt32) ENGINE = GenerateRandom(1, 5, 3)
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```
**2.** Query the data:
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``` sql
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SELECT * FROM generate_engine_table LIMIT 3
```
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``` text
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┌─name─┬──────value─┐
│ c4xJ │ 1412771199 │
│ r │ 1791099446 │
│ 7#$ │ 124312908 │
└──────┴────────────┘
```
## Details of Implementation {#details-of-implementation}
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- Not supported:
- `ALTER`
- `SELECT ... SAMPLE`
- `INSERT`
- Indices
- Replication
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[Original article](https://clickhouse.com/docs/en/operations/table_engines/generate/) <!--hide-->