Redis is a high-performance in-memory data management system based on the key–value model. It is used as a database, cache, and message broker. The main feature of Redis is that data is stored in RAM, which provides extremely fast request processing, often in the microsecond range. Redis supports complex data structures, guarantees atomic operations, and can scale horizontally through clustering and replication.
How Redis works
Redis stores data in memory, which allows read and write operations to be performed significantly faster than in traditional databases that work with disk storage. Each value is tied to a unique key. An application communicates with the Redis server through a simple protocol, sending commands such as SET, GET, INCR, LPUSH.
For long-term persistence, Redis uses snapshotting (RDB) and command logging (AOF). This approach combines high speed with fault tolerance.
Data structures
Redis supports several data types, making it far more flexible than classic key–value stores:
- strings;
- lists;
- sets and sorted sets;
- hash tables;
- bitmaps and HyperLogLog;
- streams.
Thanks to this, Redis is used in a wide range of tasks — from metric counting to queue implementation and session management.
Primary tasks solved by Redis
Redis is indispensable in scenarios that require handling large volumes of fast requests:
- caching data to reduce load on the primary database;
- storing user sessions in web applications;
- managing task and event queues;
- implementing real-time features — chats, data streaming, monitoring;
- storing counters, rankings, and timestamps;
- accelerating microservice architectures.
With proper configuration, Redis provides consistently low latency and supports high loads.
Architecture and scaling
Redis supports master–replica replication, which enables read distribution and improves fault tolerance. For scaling, Redis Cluster is used — a distributed architecture where data is partitioned across multiple nodes. If some nodes fail, the cluster automatically redistributes the load. Sentinel mechanisms provide automatic failure detection and failover to a standby node.
Examples of use
Redis is widely used in online services, SaaS platforms, gaming projects, analytics systems, and microservice infrastructures. For example, recommendation systems store computation results in Redis for fast access, e-commerce platforms use it to manage carts and sessions, and logistics companies apply it for real-time processing of order status data.