Cassandra vs VoltDB: What are the differences?

# Introduction
In this comparison, we will highlight the key differences between Cassandra and VoltDB, two popular databases in the industry.

1. **Data Model**: Cassandra is a wide-column store NoSQL database that uses a decentralized architecture, perfect for handling massive amounts of data across multiple nodes. On the other hand, VoltDB is an in-memory operational database that stores data in memory for faster processing, making it ideal for real-time applications where low-latency is crucial.
2. **Consistency**: Cassandra offers eventual consistency, meaning that updates to the database may take some time to propagate across all nodes, leading to potential data divergence temporarily. In contrast, VoltDB provides strong consistency, ensuring that all nodes have the same data at any given moment, making it more reliable for critical operations that require data accuracy.
3. **Scalability**: Cassandra provides linear scalability by adding more nodes to the cluster, allowing it to handle growing workloads effortlessly. VoltDB, on the other hand, scales vertically by adding more resources to the server, making it easier to manage for smaller deployments with lower hardware requirements.
4. **Use Case**: Cassandra is well-suited for applications requiring high availability, fault tolerance, and scalability, such as social media platforms and IoT devices. VoltDB, with its emphasis on real-time processing, is best suited for applications that demand ultra-low latency, such as financial trading platforms and telecommunications systems.
5. **Architecture**: Cassandra follows a masterless architecture where all nodes are equal, allowing for high availability and fault tolerance. In contrast, VoltDB utilizes a shared-nothing architecture where each node operates independently, minimizing inter-node communication overhead and ensuring rapid processing speed.
6. **Consolidation**: While Cassandra is designed for horizontal scaling across multiple nodes to handle vast amounts of data, VoltDB focuses on consolidating data processing in-memory on a single server, making it more suitable for real-time analytics and transactional workloads that require lightning-fast response times. 

# Summary
In summary, Cassandra and VoltDB differ in their data models, consistency levels, scalability options, use cases, architectures, and approaches to data processing, making them suitable for distinct types of applications depending on specific requirements.