ConfigsApr 11, 2026·1 min read

ScyllaDB — NoSQL Data Store Compatible with Cassandra

ScyllaDB is a high-performance NoSQL database built on the Seastar framework. Drop-in compatible with Apache Cassandra and Amazon DynamoDB APIs but 10x faster thanks to its shard-per-core, shared-nothing architecture written in C++.

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Quick Use

Use it first, then decide how deep to go

This block should tell both the user and the agent what to copy, install, and apply first.

# Docker (single node)
docker run -d --name scylla -p 9042:9042 scylladb/scylla:latest \
  --smp 2 --memory 2G --overprovisioned 1

# CQL shell
docker exec -it scylla cqlsh

CQL (Cassandra Query Language — fully compatible):

CREATE KEYSPACE tokrepo WITH replication = {
  "class": "NetworkTopologyStrategy",
  "datacenter1": 3
};

USE tokrepo;

CREATE TABLE assets (
  id uuid PRIMARY KEY,
  repo text,
  stars int,
  tags set<text>,
  created_at timestamp
);

INSERT INTO assets (id, repo, stars, tags, created_at) VALUES
  (uuid(), "react", 230000, { "frontend", "ui" }, toTimestamp(now()));

SELECT * FROM assets;
SELECT * FROM assets WHERE stars > 100000 ALLOW FILTERING;

CREATE INDEX ON assets (repo);
Intro

ScyllaDB is a distributed, wide-column NoSQL database that is drop-in compatible with Apache Cassandra (CQL protocol) and Amazon DynamoDB (via Scylla Alternator), but delivers 10x the throughput. Written in C++ on the Seastar framework with a shard-per-core, shared-nothing architecture and userspace network stack. Used at Discord, Expedia, Comcast, and Epic Games.

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

Database Protocol Architecture Language
ScyllaDB CQL + DynamoDB Shard-per-core C++
Cassandra CQL JVM threads Java
DynamoDB DynamoDB API Managed Proprietary
HBase Custom Region servers Java
Redis Cluster RESP Shard per node C

常见问题 FAQ

Q: 真的比 Cassandra 快 10x？ A: 在特定 benchmark 下是的。核心差异：C++ 无 GC、shard-per-core 无锁、userspace I/O。实际收益视工作负载而定。

Q: 迁移 Cassandra 难吗？ A: 不难。CQL 协议和驱动兼容，数据格式相同。大部分项目几小时可迁移。

Q: AGPLv3 限制？ A: 修改源码后如作为网络服务提供需开源改动部分。自用、嵌入应用不受影响。商业版有专业 support + 企业功能。

来源与致谢 Sources

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