Redis Pub/Sub vs Redis Streams: A Developer-Friendly Comparison
Redis has two powerful messaging mechanisms: Pub/Sub and Streams.
Both cater to specific needs, and understanding the difference can help you make the right choice for your use case.
Let’s break it down, developer-style.
Feature-by-Feature Breakdown
| Feature | Redis Pub/Sub | Redis Streams |
|---|---|---|
| Data Structure | Publish/subscribe mechanism | Append-only logs |
| Message Persistence | No message persistence by default | Messages are persisted in a stream |
| Message History | No message history is maintained | Message history is stored in the stream |
| Message Filtering | All messages are received by subscribers | Subscribers can filter by pattern or consumer groups |
| Message Delivery | At-least-once delivery semantics | Exactly-once delivery semantics |
| Consumer Groups | Not supported | Supported for multiple consumers |
| Scalability | Limited scalability | Scales better for large numbers of consumers |
| Message Retention | No built-in message retention | Configurable message retention |
| Use Cases | Real-time notifications | Event sourcing |
What Does This Mean for You?
Redis Pub/Sub
- Good for: Real-time notifications, chat apps, or any use case where speed and simplicity are key.
- Think of it like: A group chat where everyone hears what’s said, but once it’s said, it’s gone forever.
Redis Streams
- Good for: Event sourcing, durable message queues, and systems requiring replayable logs or advanced processing.
- Think of it like: A detailed logbook where every entry is stored and can be read whenever needed.
TL;DR
Redis Pub/Sub or Redis Streams?
The answer depends on your use case.
For real-time notifications, go with Pub/Sub. For persistence and scalability, Redis Streams is your best bet.
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Top comments (3)
Great Explanation.
Thanks :)
What's the downside to using streams Vs pub sub. It feels like you can almost use it as a queue as well if you force some concurrency in processing limit.
From what I've read you can set a limit on the stream length which actually means you can have a small level of durability or large. It just seems to offer lots of benefits.