cockroachdb

CockroachDB

CockroachDB is a cloud-native, distributed SQL database. It survives disk, machine, rack, and even datacenter failures with zero downtime. It speaks PostgreSQL.

When to Use

• Global Distributed SQL: Multi-region enterprise applications requiring PostgreSQL compatibility with multi-region write latency optimization.
• Zero-Downtime Surviving Outages: Applications requiring automated failover and self-healing data survival across region or datacenter outages.
• Strict Serializable ACID Transactions: Systems requiring the highest isolation level (Serializable) to prevent phantom reads and write skews.
• Horizontal Scaling without Sharding: Scaling relational databases beyond single-instance limits without manual application-layer sharding.

Quick Start

-- Create a table with UUID primary key for distributed scale
CREATE TABLE accounts (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    balance DECIMAL(19,4)
);

-- Distributed Transaction
BEGIN;
UPDATE accounts SET balance = balance - 100 WHERE id = 'uuid-1';
UPDATE accounts SET balance = balance + 100 WHERE id = 'uuid-2';
COMMIT;

Core Concepts

Raft Consensus Ranges & Distributed Storage

Tables are automatically split into 64MB ordered contiguous chunks called Ranges, replicated across nodes via Raft:

[ Table: orders ]
  ├── Range 1 (Keys: 000-100) ──→ Replicated via Raft (Node 1, Node 2, Node 3)
  └── Range 2 (Keys: 101-200) ──→ Replicated via Raft (Node 2, Node 3, Node 4)

Multi-Region Table Topologies (REGIONAL vs GLOBAL)

Optimizes data locality to keep data close to users and comply with data residency regulations (GDPR):

-- Multi-region database and table definition
ALTER DATABASE enterprise_crm SET PRIMARY REGION "us-east-1";
ALTER DATABASE enterprise_crm ADD REGION "eu-west-1";
ALTER DATABASE enterprise_crm ADD REGION "ap-southeast-1";

-- Regional table colocates rows in the user's home region
CREATE TABLE enterprise_crm.customers (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    region crdb_region NOT NULL,
    full_name STRING,
    email STRING
) LOCALITY REGIONAL BY ROW AS region;