Riak vs Scylla: What are the differences?

Introduction:

Riak and Scylla are both popular distributed NoSQL databases known for their high scalability and fault-tolerance capabilities. Despite sharing similar functionalities, they have key differences that set them apart.

1. Consistency Model: Riak follows an eventually consistent model, which allows a slight delay in data synchronization between nodes, prioritizing availability and partition tolerance. On the other hand, Scylla emphasizes strong consistency, ensuring that all nodes have the most up-to-date data at all times to maintain data integrity.

2. Data Model: Riak utilizes an object-oriented data model, where each piece of data is stored as an object identified by a unique key. In contrast, Scylla employs a wide-column store data model similar to Apache Cassandra, organizing data into rows and columns for efficient querying and storage.

3. Architecture: Riak is built on Erlang/OTP, a platform known for its fault-tolerance and concurrency capabilities, making Riak a robust system for handling distributed computing tasks. In contrast, Scylla is designed with C++ and the Seastar framework, leveraging high-performance features for optimized throughput and low-latency performance.

4. Partitioning Strategy: Riak uses consistent hashing to distribute data evenly across its cluster, which facilitates scalability and load balancing by ensuring that each node possesses an equal share of data. In comparison, Scylla employs a token-aware partitioner, which assigns data partitions based on consistent hashing and takes into account the physical proximity of nodes, enhancing data locality and reducing latency.

5. Secondary Indexing: Riak offers secondary indexing capabilities that enable users to perform complex queries and retrieve data based on attributes other than the primary key. On the contrary, Scylla does not support secondary indexing natively but relies on external indexing solutions like Apache Cassandra or integrated search engines for similar functionalities.

6. Performance Overhead: Due to its focus on strong consistency and transactional ACID properties, Scylla may incur higher performance overhead compared to Riak, which prioritizes eventual consistency and availability, leading to potentially faster write operations and lower latency in certain scenarios.

In Summary, Riak and Scylla differ on aspects such as consistency model, data model, architecture, partitioning strategy, secondary indexing support, and performance overhead, catering to diverse use cases based on users' preferences for consistency, scalability, and performance.