ScyllaDB vs Cassandra: What Makes ScyllaDB the Better Choice?

For years, Apache Cassandra has been a go-to NoSQL database for applications that demand high availability and horizontal scalability. It’s widely used and trusted by big names in the industry. But as workloads grow and performance becomes critical, many are starting to explore ScyllaDB a newer, high-performance alternative built with modern hardware in mind.

So what makes ScyllaDB stand out from Cassandra? Here's a look at the key differences and why more teams are making the switch.

1. C++ Instead of Java

The most fundamental difference is in the programming language. Cassandra is written in Java, which means it relies on the Java Virtual Machine (JVM) for memory management. This introduces latency issues due to garbage collection and other runtime overhead.

ScyllaDB, on the other hand, is built in C++. It doesn't use a garbage collector, which results in much more consistent performance. That means no random latency spikes or pauses under load, a major win for real-time applications.

2. Asynchronous, Shared-Nothing Design

Cassandra uses a thread-per-request model and shares memory across threads. As clusters grow, this design can become inefficient and harder to manage.

ScyllaDB was built differently. It uses an asynchronous, shared-nothing architecture where each CPU core handles its own data independently. There's no contention between threads, no locks, and no need to wait on other processes. This leads to significantly better performance, especially as the number of cores increases.

3. Thread-Per-Core Efficiency

ScyllaDB automatically distributes data across CPU cores and disks. Each core runs its own thread, dedicated to handling its portion of the data.

This "thread-per-core" model allows ScyllaDB to scale vertically with the number of cores, making full use of modern multi-core processors. It also means fewer context switches and more efficient CPU usage compared to Cassandra.

4. Predictable Latency and Higher Throughput

When benchmarked side by side, ScyllaDB consistently delivers better throughput than Cassandra  often by 3 to 10 times  while maintaining much lower latency.

Where Cassandra might show unpredictable latency, especially under load, ScyllaDB remains stable and responsive. This is a big advantage for applications like recommendation engines, fraud detection, and IoT platforms where every millisecond counts.

5. Easy Migration with CQL Compatibility

ScyllaDB supports the Cassandra Query Language (CQL), which means it’s API-compatible with Cassandra. Most applications that use Cassandra can be pointed to a ScyllaDB cluster with little or no code changes.

There are also tools provided by ScyllaDB, like the Scylla Migrator, that help automate and simplify the migration process.

6. Easier to Manage and Self-Tuning

One of the pain points with Cassandra is the need to tune dozens of JVM settings, compaction strategies, and cache configurations. It often requires deep expertise to operate Cassandra efficiently at scale.

ScyllaDB simplifies all of this. It is largely self-tuning and handles most configuration tasks automatically. This reduces the need for constant tweaking and makes it easier for smaller teams to manage large deployments.

7. Built-In Monitoring and Management Tools

ScyllaDB comes with built-in tools like Scylla Manager for maintenance tasks and a preconfigured monitoring stack based on Prometheus and Grafana. These tools make it easier to keep an eye on cluster health, schedule repairs, and run backups.

Cassandra has monitoring options too, but many require third-party tools or enterprise licensing.

8. Lower Total Cost of Ownership

Because of its efficiency, ScyllaDB typically requires fewer nodes to handle the same workload as Cassandra. That means you can achieve better performance with less infrastructure, which directly translates to cost savings.

In real-world deployments, some companies have reported reducing their cluster size by half or more after switching to ScyllaDB without sacrificing performance.

 

Why Choose ScyllaDB? 

Features	Apache Cassandra	ScyllaDB
Language	Java	C++
Garbage Collection	Yes (JVM)	No
Architecture	Thread-per-request	Shared-nothing, async
CPU Efficiency	Moderate	High (thread-per-core)
Latency	Variable	Predictable and low
Throughput	Good	3x to 10x better
Operational Complexity	High	Low
Compatibility	CQL	CQL + DynamoDB API
Cost	Higher	Lower (fewer nodes needed)

Final Thoughts

Cassandra has served many companies well, and for good reason. But ScyllaDB builds on the same principles and takes them further with better performance, lower latency, easier operations, and a much lower cost of ownership.

If you're already using Cassandra and feeling the limits, or if you're starting a new project that demands speed and scalability, ScyllaDB is worth serious consideration. It’s a modern database for the modern era without the headaches.