CockroachDB — Distributed SQL for the Global Cloud

What CockroachDB Does

• Serializable transactions — strongest ACID guarantee
• PostgreSQL compatibility — wire protocol + most SQL features
• Auto-sharding — data split into ranges, auto-rebalanced
• Multi-region — place data near users via zone configs
• Raft replication — configurable replica count per table
• Online schema changes — non-blocking DDL
• Time travel queries — AS OF SYSTEM TIME
• Follower reads — read from closest replica for low latency
• CDC — change data capture stream

Architecture

Each node is identical (no primary/secondary). Data is split into 64MB ranges, each replicated via Raft to typically 3 nodes. SQL layer sits on top of the distributed KV layer. DistSQL executes queries across nodes in parallel.

Self-Hosting

# Secure 3-node cluster
cockroach start --certs-dir=certs --listen-addr=node1:26257 \
  --advertise-addr=node1 \
  --join=node1,node2,node3

# Init cluster
cockroach init --certs-dir=certs --host=node1

Key Features

• Distributed SQL with serializable transactions
• PostgreSQL wire compatibility
• Multi-region with geo-partitioning
• Automatic sharding and rebalancing
• Zero-downtime upgrades
• Online schema changes
• Backup and restore
• Row-level TTL
• Change data capture
• BACKUP to cloud storage

Comparison

FAQ

Q: A PostgreSQL drop-in? A: Most PostgreSQL features are compatible. Incompatibilities include: stored procedures (limited support), certain types, and some PG extensions. Test before migrating.

Q: Performance overhead? A: Distributed transactions are slower than single-machine (latency ≈ 2-3 network RTTs). But the horizontal scaling capability far surpasses a single machine. For small apps, single-node Postgres is faster and cheaper.

Q: BUSL restrictions? A: Source is readable and self-usable, but you cannot run a commercial managed service that competes with Cockroach Cloud. Automatically converts to Apache 2.0 after 4 years.

Sources

• Docs: https://www.cockroachlabs.com/docs
• GitHub: https://github.com/cockroachdb/cockroach
• License: BUSL 1.1