Cloudflare D1: Serverless SQLite at the Edge — Production Patterns

Cloudflare D1 is SQLite running inside Workers. You get sub-5ms query latency at the edge, zero ops, and $0 for most hobby and early-stage SaaS workloads. Here's how to use it in production.

Why D1 Over Planetscale or Neon

	D1	PlanetScale	Neon
Latency	<5ms (edge)	10-50ms	10-50ms
Free tier	5M rows/day reads	5B rows/mo	0.5 GB storage
Pricing at scale	$0.001/M reads	$39+/mo	$19+/mo
Engine	SQLite	MySQL	PostgreSQL
Vendor	Cloudflare	PlanetScale	Neon

D1 wins on latency for edge-deployed apps. The SQLite limitation is real but manageable.

Setup

npm create cloudflare@latest my-app -- --framework=next
cd my-app
wrangler d1 create my-db

Add to wrangler.toml:

[[d1_databases]]
binding = "DB"
database_name = "my-db"
database_id = "your-database-id-here"

Schema and Migrations

D1 uses SQL migrations, not an ORM migration system:

# Create migration
wrangler d1 migrations create my-db add-users-table

-- migrations/0001_add_users_table.sql
CREATE TABLE users (
  id TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
  email TEXT NOT NULL UNIQUE,
  plan TEXT NOT NULL DEFAULT 'free',
  created_at INTEGER NOT NULL DEFAULT (unixepoch())
);

CREATE INDEX idx_users_email ON users(email);

# Apply locally
wrangler d1 migrations apply my-db --local

# Apply to production
wrangler d1 migrations apply my-db --remote

Querying in Workers

// worker.ts
interface Env {
  DB: D1Database;
}

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const { results } = await env.DB.prepare(
      'SELECT * FROM users WHERE plan = ? LIMIT ?'
    )
    .bind('pro', 100)
    .all<User>();

    return Response.json(results);
  },
};

With Drizzle ORM (Recommended)

npm install drizzle-orm
npm install -D drizzle-kit

// db/schema.ts
import { sqliteTable, text, integer } from 'drizzle-orm/sqlite-core';
import { sql } from 'drizzle-orm';

export const users = sqliteTable('users', {
  id: text('id').primaryKey().$defaultFn(() => crypto.randomUUID()),
  email: text('email').notNull().unique(),
  plan: text('plan', { enum: ['free', 'pro', 'enterprise'] }).default('free').notNull(),
  createdAt: integer('created_at', { mode: 'timestamp' })
    .default(sql`(unixepoch())`).notNull(),
});

// db/index.ts
import { drizzle } from 'drizzle-orm/d1';
import * as schema from './schema';

export function getDb(env: Env) {
  return drizzle(env.DB, { schema });
}

// Usage in worker
const db = getDb(env);

// Type-safe queries
const proUsers = await db
  .select()
  .from(schema.users)
  .where(eq(schema.users.plan, 'pro'))
  .limit(50);

D1 in Next.js (Pages on Cloudflare)

// app/api/users/route.ts
import { getRequestContext } from '@cloudflare/next-on-pages';
import { getDb } from '@/db';

export const runtime = 'edge';

export async function GET() {
  const { env } = getRequestContext();
  const db = getDb(env);

  const users = await db.select().from(schema.users);
  return Response.json(users);
}

Production Patterns

Batch Writes (Avoid N+1)

// ❌ N+1 writes — slow
for (const user of users) {
  await env.DB.prepare('INSERT INTO users (id, email) VALUES (?, ?)')
    .bind(user.id, user.email)
    .run();
}

// ✅ Batch in one round-trip
const stmts = users.map(user =>
  env.DB.prepare('INSERT INTO users (id, email) VALUES (?, ?)')
    .bind(user.id, user.email)
);
await env.DB.batch(stmts);

Transactions

// D1 supports transactions via batch with implicit transaction
const results = await env.DB.batch([
  env.DB.prepare('UPDATE accounts SET balance = balance - ? WHERE id = ?')
    .bind(100, fromId),
  env.DB.prepare('UPDATE accounts SET balance = balance + ? WHERE id = ?')
    .bind(100, toId),
]);
// Both statements run atomically

Read Replicas (Global Distribution)

D1 automatically replicates reads to the nearest Cloudflare PoP. Writes go to the primary (currently one region). For read-heavy workloads this is effectively global:

User in Tokyo → reads from Tokyo PoP (<5ms)
User in London → reads from London PoP (<5ms)
All writes → primary region (~50ms for write, then async replication)

D1 Limits to Know

• Max DB size: 2GB (free), 10GB (Workers Paid)
• Max row size: 1MB
• No full-text search: Use Cloudflare Vectorize or an external search service
• No stored procedures: Application-layer logic only
• SQLite-specific: TEXT for UUIDs, INTEGER for timestamps (Unix epoch)

When Not to Use D1

• Multi-tenant apps where each tenant needs an isolated DB (use Workers KV or separate D1 per tenant instead)
• Apps with heavy write throughput (>1k writes/sec) — D1's write path still routes to a single region
• Complex JOIN-heavy analytics — better to use a separate OLAP store

For typical SaaS with more reads than writes, D1 is a compelling choice that eliminates database ops entirely.

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Running D1 in production? What workload and what limits have you hit? Comment below.