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68 lines
1.8 KiB
Markdown
68 lines
1.8 KiB
Markdown
---
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slug: /en/sql-reference/table-functions/redis
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sidebar_position: 170
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sidebar_label: redis
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---
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# redis
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This table function allows integrating ClickHouse with [Redis](https://redis.io/).
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**Syntax**
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```sql
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redis(host:port, key, structure[, db_index[, password[, pool_size]]])
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```
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**Arguments**
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- `host:port` — Redis server address, you can ignore port and default Redis port 6379 will be used.
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- `key` — any column name in the column list.
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- `structure` — The schema for the ClickHouse table returned from this function.
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- `db_index` — Redis db index range from 0 to 15, default is 0.
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- `password` — User password, default is blank string.
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- `pool_size` — Redis max connection pool size, default is 16.
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- `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.
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- columns other than the primary key will be serialized in binary as Redis value in corresponding order.
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- 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.
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**Returned Value**
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A table object with key as Redis key, other columns packaged together as Redis value.
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## Usage Example {#usage-example}
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Create a table in ClickHouse which allows to read data from Redis:
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``` sql
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CREATE TABLE redis_table
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(
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`k` String,
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`m` String,
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`n` UInt32
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)
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ENGINE = Redis('redis1:6379') PRIMARY KEY(k);
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```
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```sql
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SELECT * FROM redis(
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'redis1:6379',
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'key',
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'key String, v1 String, v2 UInt32'
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)
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```
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**See Also**
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- [The `Redis` table engine](/docs/en/engines/table-engines/integrations/redis.md)
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- [Using redis as a dictionary source](/docs/en/sql-reference/dictionaries/index.md#redis)
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