ClickHouse/docs/en/sql-reference/table-functions/redis.md

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/en/sql-reference/table-functions/redis	43	redis

redis

This table function allows integrating ClickHouse with Redis.

Syntax

redis(host:port, key, structure[, db_index[, password[, pool_size]]])

Arguments

• host:port — Redis server address, you can ignore port and default Redis port 6379 will be used.

• key — any column name in the column list.

• structure — The schema for the ClickHouse table returned from this function.

• db_index — Redis db index range from 0 to 15, default is 0.

• password — User password, default is blank string.

• pool_size — Redis max connection pool size, default is 16.

• primary must be specified, it supports only one column in the primary key. The primary key will be serialized in binary as a Redis key.

• columns other than the primary key will be serialized in binary as Redis value in corresponding order.

• queries with key equals or in filtering will be optimized to multi keys lookup from Redis. If queries without filtering key full table scan will happen which is a heavy operation.

Returned Value

A table object with key as Redis key, other columns packaged together as Redis value.

Usage Example

Create a table in ClickHouse which allows to read data from Redis:

CREATE TABLE redis_table
(
    `k` String,
    `m` String,
    `n` UInt32
)
ENGINE = Redis('redis1:6379') PRIMARY KEY(k);

SELECT * FROM redis(
    'redis1:6379',
    'key',
    'key String, v1 String, v2 UInt32'
)

See Also

• The Redis table engine
• Using redis as a dictionary source