GenerateRandom
The GenerateRandom table engine produces random data for given table schema.
Usage examples:
- Use in test to populate reproducible large table.
- Generate random input for fuzzing tests.
Usage in ClickHouse Server
ENGINE = GenerateRandom(random_seed, max_string_length, max_array_length)
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 that can be stored in a table except LowCardinality
and AggregateFunction
.
Example:
1. Set up the generate_engine_table
table:
CREATE TABLE generate_engine_table (name String, value UInt32) ENGINE = GenerateRandom(1, 5, 3)
2. Query the data:
SELECT * FROM generate_engine_table LIMIT 3
┌─name─┬──────value─┐
│ c4xJ │ 1412771199 │
│ r │ 1791099446 │
│ 7#$ │ 124312908 │
└──────┴────────────┘
Details of Implementation
- Not supported:
ALTER
SELECT ... SAMPLE
INSERT
- Indices
- Replication
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