Compare Dqlite vs. Voldemort

Dqlite is a high-speed, embedded SQL database that offers persistent storage and utilizes Raft consensus, making it an ideal choice for resilient IoT and Edge devices. Known as "distributed SQLite," Dqlite expands SQLite's capabilities across multiple machines, ensuring automatic failover and high availability to maintain application uptime. It employs C-Raft, an optimized implementation of Raft in C, which provides exceptional performance in transactional consensus and fault tolerance while maintaining SQLite’s renowned efficiency and compact size. C-Raft is specifically designed to reduce transaction latency, enabling faster operations. Both C-Raft and Dqlite are implemented in C, ensuring they are portable across various platforms. Released under the LGPLv3 license with a static linking exception, it guarantees broad compatibility. The system features a standard CLI pattern for initializing databases and managing the joining or leaving of voting members. It also incorporates minimal, configurable delays for failover alongside automatic leader election processes. Additionally, Dqlite supports a disk-backed database option with in-memory capabilities and adheres to SQLite's transaction protocols. The blend of these features makes Dqlite a powerful solution for modern data storage needs.

Voldemort does not function as a relational database, as it does not aim to fulfill arbitrary relations while adhering to ACID properties. It also does not operate as an object database that seeks to seamlessly map object reference structures. Additionally, it does not introduce a novel abstraction like document orientation. Essentially, it serves as a large, distributed, durable, and fault-tolerant hash table. For applications leveraging an Object-Relational (O/R) mapper such as ActiveRecord or Hibernate, this can lead to improved horizontal scalability and significantly enhanced availability, albeit with a considerable trade-off in convenience. In the context of extensive applications facing the demands of internet-level scalability, a system is often comprised of multiple functionally divided services or APIs, which may handle storage across various data centers with their own horizontally partitioned storage systems. In these scenarios, the possibility of performing arbitrary joins within the database becomes impractical, as not all data can be accessed within a single database instance, making data management even more complex. Consequently, developers must adapt their strategies to navigate these limitations effectively.