ScyllaDB — NoSQL Data Store Compatible with Cassandra

What ScyllaDB Does

• CQL compatibility — drop-in for Cassandra
• DynamoDB compatibility — via Alternator
• Shard-per-core — one thread per CPU core, no lock contention
• User-space I/O — bypass kernel for networking and storage
• Workload prioritization — classify and prioritize queries
• Incremental compaction — avoid disk space amplification
• Materialized views — auto-maintained denormalized tables
• LWT (lightweight transactions) — Paxos-based linearizable operations
• Change Data Capture — stream CDC events

Architecture

Built on Seastar (userspace C++ framework). Each CPU core owns a shard of data with no shared state — eliminating lock contention and context switching. Userspace TCP stack (DPDK optional) and direct I/O to disk.

Self-Hosting

# 3-node cluster
version: "3"
services:
  scylla-node1:
    image: scylladb/scylla:latest
    command: --seeds=scylla-node1 --smp 4 --memory 8G
  scylla-node2:
    image: scylladb/scylla:latest
    command: --seeds=scylla-node1 --smp 4 --memory 8G
  scylla-node3:
    image: scylladb/scylla:latest
    command: --seeds=scylla-node1 --smp 4 --memory 8G

Key Features

• Cassandra + DynamoDB wire compatibility
• Shard-per-core architecture
• Sub-millisecond P99 latency
• Linear scaling
• Workload prioritization
• Incremental compaction
• Materialized views
• Change Data Capture
• ScyllaDB Manager for ops
• ScyllaDB Monitoring Stack

Comparison

FAQ

Q: Is it really 10x faster than Cassandra? A: Yes under specific benchmarks. Key differences: C++ without GC, shard-per-core lock-free design, and userspace I/O. Actual gains depend on your workload.

Q: Is migrating from Cassandra hard? A: No. The CQL protocol and drivers are compatible, and the data format is the same. Most projects can migrate in a few hours.

Q: AGPLv3 restrictions? A: If you modify the source and offer it as a network service, you must open source your modifications. Self-use and embedding in applications are not affected. The commercial edition includes professional support and enterprise features.

Sources

• Docs: https://docs.scylladb.com
• GitHub: https://github.com/scylladb/scylladb
• License: AGPLv3