Hazelcast vs Redis: What are the differences?

Introduction

Markdown code comparing the key differences between Hazelcast and Redis.

1. In-Memory Data Grid vs. NoSQL Database: Hazelcast is primarily an in-memory data grid (IMDG) that stores and processes data in memory, providing fast access and low latency. On the other hand, Redis is a NoSQL database that persists data on disk and also supports in-memory caching. This fundamental difference influences their use cases, with Hazelcast being better suited for scenarios requiring real-time data processing and Redis for data persistence and caching.

2. Data Models: Hazelcast supports a wide range of data structures such as distributed maps, queues, sets, and lists, allowing for complex data models and distributed computations. Redis, on the other hand, focuses on simpler data structures like strings, hashes, lists, sets, and sorted sets, emphasizing efficiency and simplicity.

3. Consistency and Durability: Hazelcast provides strong data consistency guarantees through its distributed data structures. It ensures that data is always synchronized across the cluster, even in the presence of failures. Redis, on the other hand, offers eventual consistency by default, where data updates may take some time to propagate across nodes. Additionally, Redis allows users to choose different persistence mechanisms like snapshots or append-only logs for data durability.

4. Programming Language Support: Hazelcast provides official clients for multiple programming languages, including Java, .NET, C++, Python, and Node.js, enabling developers to integrate it seamlessly into their application stack. Redis also offers official clients for a wide range of programming languages, making it accessible for different development environments.

5. Distributed Computing Capabilities: Hazelcast includes a distributed computing framework, enabling distributed processing of data across the cluster using parallel algorithms. It supports distributed tasks, computing grid, event-driven programming, and distributed execution of user-defined functions. Redis, on the other hand, does not provide built-in distributed computing capabilities, focusing more on data operations and caching.

6. Scalability and Fault-Tolerance: Both Hazelcast and Redis support horizontal scalability, allowing users to add or remove nodes dynamically to accommodate growing or shrinking workloads. However, Hazelcast provides automatic data replication, ensuring fault-tolerance even in the event of node failures. Redis requires users to configure replication manually to achieve fault-tolerance.

In summary, Hazelcast is an in-memory data grid with strong consistency and distributed computing capabilities, while Redis is a NoSQL database with a focus on simplicity, efficiency, and caching.