RESP 3 Features

As of version 5.0, redis-py supports the RESP 3 standard. Starting with redis-py 8.0, clients use RESP3 on the wire by default.

By default, redis-py keeps legacy RESP2-compatible Python response shapes for existing applications. Set protocol=3 explicitly when your application should receive RESP3-specific Python response shapes or when you want the wire protocol choice to be visible in code. Set protocol=2 to force RESP2 on the wire. Set legacy_responses=False to opt in to protocol-independent unified response shapes; see Migrate to Unified Responses.

Connecting

The default connection already uses RESP3 on the wire in redis-py 8.0 and later while preserving legacy RESP2-compatible Python response shapes. The following examples show how to set protocol=3 explicitly when you want RESP3-specific response shapes or visible protocol configuration for standard, async, and cluster clients.

Connect with a standard connection, explicitly specifying RESP3:

>>> import redis
>>> r = redis.Redis(host='localhost', port=6379, protocol=3)
>>> r.ping()

Or using the URL scheme:

>>> import redis
>>> r = redis.from_url("redis://localhost:6379?protocol=3")
>>> r.ping()

Connect with async, explicitly specifying RESP3:

>>> import redis.asyncio as redis
>>> r = redis.Redis(host='localhost', port=6379, protocol=3)
>>> await r.ping()

The URL scheme with the async client

>>> import redis.asyncio as Redis
>>> r = redis.from_url("redis://localhost:6379?protocol=3")
>>> await r.ping()

Connecting to an OSS Redis Cluster with RESP 3

>>> from redis.cluster import RedisCluster, ClusterNode
>>> r = RedisCluster(startup_nodes=[ClusterNode('localhost', 6379), ClusterNode('localhost', 6380)], protocol=3)
>>> r.ping()

Push notifications

Push notifications are a way that redis sends out of band data. The RESP 3 protocol includes a push type that allows our client to intercept these out of band messages. By default, clients will log simple messages, but redis-py includes the ability to bring your own function processor.

This means that should you want to perform something, on a given push notification, you specify a function during the connection, as per this examples:

>> from redis import Redis
>>
>> def our_func(message):
>>    if message.find("This special thing happened"):
>>        raise IOError("This was the message: \n" + message)
>>
>> r = Redis(protocol=3)
>> p = r.pubsub(push_handler_func=our_func)

In the example above, upon receipt of a push notification, rather than log the message, in the case where specific text occurs, an IOError is raised. This example, highlights how one could start implementing a customized message handler.

Client-side caching

Client-side caching is a technique used to create high performance services. It utilizes the memory on application servers, typically separate from the database nodes, to cache a subset of the data directly on the application side. For more information please check the Redis client-side caching documentation. Please notice that this feature is available only with RESP3 protocol enabled in sync clients. redis-py 8.0 and later use RESP3 on the wire by default, and the examples below pass protocol=3 explicitly to make the requirement clear. Supported in standalone, Cluster, and Sentinel clients.

Basic usage:

Enable caching with default configuration:

>>> import redis
>>> from redis.cache import CacheConfig
>>> r = redis.Redis(host='localhost', port=6379, protocol=3, cache_config=CacheConfig())

The same interface applies to Redis Cluster and Sentinel.

Enable caching with custom cache implementation:

>>> import redis
>>> from foo.bar import CacheImpl
>>> r = redis.Redis(host='localhost', port=6379, protocol=3, cache=CacheImpl())

CacheImpl should implement a CacheInterface specified in redis.cache package.

More comprehensive documentation soon will be available at the Redis documentation site.