Memcached vs NuoDB: What are the differences?

Introduction: In the world of databases and caching systems, Memcached and NuoDB are two popular choices. Below are the key differences between Memcached and NuoDB.

1. Architecture: Memcached is a distributed memory caching system that stores data in memory for faster access, acting as a key-value store. On the other hand, NuoDB is a distributed SQL database designed to scale-out elastically and guarantee ACID properties across multiple nodes. While Memcached is primarily used for caching data to improve performance, NuoDB is designed to store and manage structured data in a distributed environment.

2. Consistency: Memcached focuses on speed and scalability, sacrificing consistency in favor of performance. It uses a loose form of consistency known as eventual consistency, where data updates may take time to propagate across all nodes. In contrast, NuoDB ensures strong consistency by using a distributed commit protocol that guarantees the execution and order of transactions across the database in a consistent manner.

3. Data Storage: Memcached stores data in memory only and does not provide persistence mechanisms out of the box. Data is lost upon server restarts or crashes unless backed up externally. In contrast, NuoDB can store data both in memory and on disk, ensuring data durability and fault tolerance through replication and persistence mechanisms.

4. Query Language: Memcached does not support querying or any form of SQL-like operations as it is a simple key-value store. In contrast, NuoDB supports standard SQL queries and transactions, providing a familiar interface for developers and enabling complex data retrieval and manipulation operations.

5. Scaling: Memcached scales horizontally by adding more servers to the pool, distributing the workload and data across multiple nodes. However, it relies on client-side sharding and may require application-level logic to manage data distribution. NuoDB, on the other hand, scales both vertically and horizontally by adding more compute or storage nodes, automatically distributing data and workload without the need for manual sharding.

6. Consensus Protocol: Memcached does not employ a consensus protocol for coordination between nodes, making it susceptible to data inconsistencies in case of network partitions. NuoDB, on the other hand, uses a distributed consensus protocol like Paxos or Raft to ensure coordination and agreement among nodes, maintaining data integrity and consistency even in the presence of network failures.

In Summary, Memcached focuses on speed and caching performance with eventual consistency, while NuoDB prioritizes ACID compliance, strong consistency, and distributed SQL capabilities for scalable and reliable data storage.