MySQL vs Scylla: What are the differences?

Introduction:

MySQL and Scylla are both popular database management systems, but they have significant differences in various aspects. Here are six key differences between MySQL and Scylla:

1. Architecture: MySQL follows a traditional architecture known as the shared-disk model, where all nodes communicate with a central storage component. On the other hand, Scylla is built on the shared-nothing architecture, where each node operates independently with its own storage. This architecture leads to improved scalability and fault tolerance in Scylla.

2. Data Model: MySQL uses a relational data model, allowing data to be organized into tables with defined relationships between them. Scylla, on the contrary, is based on a wide-column data model and supports a schema-less approach, where data can be stored in flexible column families. This enables better handling of unstructured and rapidly changing data in Scylla.

3. Consistency: MySQL emphasizes immediate consistency, ensuring that all clients see the same version of data at a specific point in time. In Scylla, eventual consistency is the default, which means that different clients might observe different versions of data for a certain period. However, Scylla provides configurable tunings to adjust the level of consistency as per application requirements.

4. Performance: Scylla is designed to deliver high performance and low latency, particularly for large-scale distributed systems. It achieves this through its memory-centric architecture that takes full advantage of RAM and solid-state drives. MySQL, though capable of handling significant workloads, may face scalability challenges when dealing with huge datasets or high traffic loads.

5. Replication: MySQL utilizes synchronous replication, where write operations are committed to multiple nodes before being acknowledged. This ensures data durability but introduces some latency. In contrast, Scylla employs asynchronous replication, allowing faster write operations but potential data loss if a node fails before synchronizing the data.

6. Availability: MySQL relies on a master-slave replication model for high availability, where a single master node handles writes while multiple slave nodes handle reads. If the master node fails, failover is required to promote one of the slaves as the new master. In Scylla, multi-master replication is native, allowing all nodes to handle both read and write operations, thereby eliminating the single point of failure.

In Summary, MySQL and Scylla differ in their architecture, data models, consistency models, performance characteristics, replication methods, and availability approaches. These differences make them suitable for different use cases depending on specific requirements, scalability needs, and latency sensitivities.