The Redis String sink writes database changes to a Redis instance as key-value pairs using the Redis String data type.

This is the reference for the Redis String sink. See the quickstart for a step-by-step walkthrough or the how-to guide for an explanation of how to use the Redis String sink.

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Configuration parameters

ParameterTypeRequiredDefaultDescription
hoststringYes-Hostname or IP address of the Redis server
portintegerYes-Port number of the Redis server (1-65535)
usernamestringNo-Username for Redis authentication
passwordstringNo-Password for Redis authentication
tlsbooleanNofalseEnable TLS/SSL for the connection
databaseintegerNo0Redis database number (≥ 0)
expire_msintegerNo-Key expiration time in milliseconds (≥ 0, omit for no expiration)

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Redis connection

The sink connects to Redis using the following URL format:

redis[s]://[username:password@]host:port/database

Where:

  • rediss:// is used when tls is enabled, otherwise redis://
  • Authentication credentials are included when provided

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Key format and operations

For each change to the source table, the sink performs the following Redis operations:

Change actionRedis operationBehavior
INSERT, UPDATE, READSETSets the key to the JSON representation of the record
DELETEDELRemoves the key from Redis

By default, keys are generated using the format:

sequin:{table_name}:{primary_key}

For composite primary keys, values are joined with a colon.

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Routing

You can use a routing function to customize the key used for each message. For example, you can use the record’s id field with your own prefix:

def route(action, record, changes, metadata) do
  %{
    key: "my_app:users:#{record["id"]}"
  }
end

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Data format

Records are stored as JSON strings. The specific format depends on the transform applied to the data:

With no transform, the entire message payload is stored as a JSON object

This may not be preferred for most caching use cases. We recommend using a transform to modify the structure and content before storage.

If your transform returns a string or binary-coercible value (such as an integer or boolean), the value is stored directly in Redis.

Otherwise, Sequin will JSON encode the value before storing it in Redis.

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Key expiration

When expire_ms is specified, each key is set with an expiration time using Redis’ PX operation during SET. This allows for automatic key cleanup.