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

---
slug: /en/sql-reference/table-functions/redis
sidebar_position: 10
sidebar_label: Redis
---

# Redis

This table function allows integrating ClickHouse with [Redis](https://redis.io/).

**Syntax**

```sql
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 {#usage-example}

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

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

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

**See Also**

- [The `Redis` table engine](/docs/en/engines/table-engines/integrations/redis.md)
- [Using redis as a dictionary source](/docs/en/sql-reference/dictionaries/index.md#redis)