UUID Generation: Choosing the Right Version

Generating UUIDs in JavaScript

// UUID v4 - Native browser/Node.js support
const uuidv4 = crypto.randomUUID();
console.log(uuidv4); // "f47ac10b-58cc-4372-a567-0e02b2c3d479"

// UUID v7 - Using the 'uuid' package
import { v7 as uuidv7 } from 'uuid';
const uuidV7 = uuidv7();
console.log(uuidV7); // "018e9d1c-e4a1-7b5c-9abc-def012345678"

// Custom UUID v7 implementation (if no library)
function generateUUIDv7() {
  const timestamp = Date.now();
  const timestampHex = timestamp.toString(16).padStart(12, '0');
  
  const randomBytes = new Uint8Array(10);
  crypto.getRandomValues(randomBytes);
  
  // Set version (7) and variant bits
  randomBytes[0] = (randomBytes[0] & 0x0f) | 0x70;
  randomBytes[2] = (randomBytes[2] & 0x3f) | 0x80;
  
  const randomHex = Array.from(randomBytes)
    .map(b => b.toString(16).padStart(2, '0'))
    .join('');
  
  return `${timestampHex.slice(0, 8)}-${timestampHex.slice(8)}-${randomHex.slice(0, 4)}-${randomHex.slice(4, 8)}-${randomHex.slice(8)}`;
}

UUID in Database Schemas (PostgreSQL)

-- PostgreSQL has native UUID support
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

-- Table with UUID v4 primary key (random)
CREATE TABLE users_v4 (
  id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
  email VARCHAR(255) NOT NULL,
  created_at TIMESTAMP DEFAULT NOW()
);

-- For UUID v7, use gen_random_uuid() or application-generated
-- Note: Native v7 support coming in future PostgreSQL versions

-- Validate UUID format
SELECT id FROM users_v4 
WHERE id::text ~ '^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$';