Redis vs Streaming Databases for Real-Time Data Serving
Redis is an in-memory key-value store used for caching and real-time data serving. Streaming databases like RisingWave continuously compute and serve pre-aggregated results via SQL. Use Redis for simple key-value lookups with sub-millisecond latency. Use a streaming database when your "cache" is actually a pre-computed aggregation that needs to stay in sync with source data.
Comparison
| Feature | Redis | RisingWave |
| Data model | Key-value (strings, hashes, sets, sorted sets) | SQL tables + materialized views |
| Query language | Redis commands | PostgreSQL SQL |
| Latency | Sub-millisecond | 10-20ms p99 |
| Data freshness | Manual update (application writes) | Automatic (streaming computation) |
| Aggregations | Manual (application logic) | SQL (COUNT, SUM, AVG, JOIN) |
| Persistence | Optional (RDB/AOF) | S3 (durable by default) |
| Cache invalidation | Manual TTL / application logic | Automatic (streaming keeps views current) |
| SQL support | ❌ | ✅ PostgreSQL-compatible |
The Cache Invalidation Problem
Redis requires your application to keep cached data in sync with source databases. This means:
- Write to database
- Invalidate/update Redis
- Handle race conditions, stale data, cache misses
A streaming database eliminates this entirely — materialized views stay in sync automatically via CDC.
Traditional: App → Database → App invalidates Redis → Redis serves stale-proof data
Streaming: Database → CDC → RisingWave MV → App queries fresh data via SQL
When Redis is Still Better
- Sub-millisecond latency requirements (RisingWave is 10-20ms)
- Simple key-value lookups (not aggregations)
- Session storage, rate limiting, pub/sub
- Leaderboards with sorted sets (though RisingWave can do this with SQL)
Frequently Asked Questions
Can RisingWave replace Redis?
For pre-computed aggregations and real-time views, yes — RisingWave eliminates cache invalidation. For sub-millisecond key-value lookups, session storage, and pub/sub, Redis remains better.
Is RisingWave slower than Redis?
Yes, for raw lookups. Redis serves in sub-millisecond; RisingWave in 10-20ms. But RisingWave computes aggregations automatically; with Redis, your application must compute and cache them manually.
