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---
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toc_priority: 46
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toc_title: 随机数生成
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---
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# 随机数生成表引擎 {#table_engines-generate}
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2021-07-29 15:20:55 +00:00
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随机数生成表引擎为指定的表模式生成随机数
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使用示例:
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- 测试时生成可复写的大表
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- 为复杂测试生成随机输入
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## CH服务端的用法 {#usage-in-clickhouse-server}
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``` sql
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ENGINE = GenerateRandom(random_seed, max_string_length, max_array_length)
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```
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生成数据时,通过`max_array_length` 设置array列的最大长度, `max_string_length`设置string数据的最大长度
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该引擎仅支持 `SELECT` 查询语句.
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该引擎支持能在表中存储的所有数据类型 [DataTypes](../../../sql-reference/data-types/index.md) ,除了 `LowCardinality` 和 `AggregateFunction`.
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## 示例 {#example}
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**1.** 设置 `generate_engine_table` 引擎表:
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``` sql
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CREATE TABLE generate_engine_table (name String, value UInt32) ENGINE = GenerateRandom(1, 5, 3)
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```
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**2.** 查询数据:
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``` sql
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SELECT * FROM generate_engine_table LIMIT 3
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```
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``` text
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┌─name─┬──────value─┐
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│ c4xJ │ 1412771199 │
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│ r │ 1791099446 │
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│ 7#$ │ 124312908 │
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└──────┴────────────┘
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```
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## 实现细节 {#details-of-implementation}
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- 以下特性不支持:
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- `ALTER`
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- `SELECT ... SAMPLE`
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- `INSERT`
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- Indices
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- Replication
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2021-09-19 20:05:54 +00:00
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[原始文档](https://clickhouse.com/docs/en/operations/table_engines/generate/) <!--hide-->
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