Neon Postgres

Expert patterns for Neon serverless Postgres, branching, connection pooling, and Prisma/Drizzle integration

Patterns

Prisma with Neon Connection

Configure Prisma for Neon with connection pooling.

Use two connection strings:

• DATABASE_URL: Pooled connection for Prisma Client
• DIRECT_URL: Direct connection for Prisma Migrate

The pooled connection uses PgBouncer for up to 10K connections. Direct connection required for migrations (DDL operations).

Code_example

.env

Pooled connection for application queries

DATABASE_URL="postgres://user:password@ep-xxx-pooler.us-east-2.aws.neon.tech/neondb?sslmode=require"

Direct connection for migrations

DIRECT_URL="postgres://user:password@ep-xxx.us-east-2.aws.neon.tech/neondb?sslmode=require"

// prisma/schema.prisma generator client { provider = "prisma-client-js" }

datasource db { provider = "postgresql" url = env("DATABASE_URL") directUrl = env("DIRECT_URL") }

model User { id String @id @default(cuid()) email String @unique name String? createdAt DateTime @default(now()) updatedAt DateTime @updatedAt }

// lib/prisma.ts import { PrismaClient } from '@prisma/client';

const globalForPrisma = globalThis as unknown as { prisma: PrismaClient | undefined; };

export const prisma = globalForPrisma.prisma ?? new PrismaClient({ log: process.env.NODE_ENV === 'development' ? ['query', 'error', 'warn'] : ['error'], });

if (process.env.NODE_ENV !== 'production') { globalForPrisma.prisma = prisma; }

// Run migrations // Uses DIRECT_URL automatically npx prisma migrate dev npx prisma migrate deploy

Anti_patterns

• Pattern: Using pooled connection for migrations | Why: DDL operations fail through PgBouncer | Fix: Set directUrl in schema.prisma
• Pattern: Not using connection pooling | Why: Serverless functions exhaust connection limits | Fix: Use -pooler endpoint in DATABASE_URL

References

• https://neon.com/docs/guides/prisma
• https://www.prisma.io/docs/orm/overview/databases/neon

Drizzle with Neon Serverless Driver

Use Drizzle ORM with Neon's serverless HTTP driver for edge/serverless environments.

Two driver options:

• neon-http: Single queries over HTTP (fastest for one-off queries)
• neon-serverless: WebSocket for transactions and sessions

Code_example

Install dependencies

npm install drizzle-orm @neondatabase/serverless npm install -D drizzle-kit

// lib/db/schema.ts import { pgTable, serial, text, timestamp } from 'drizzle-orm/pg-core';

export const users = pgTable('users', { id: serial('id').primaryKey(), email: text('email').notNull().unique(), name: text('name'), createdAt: timestamp('created_at').defaultNow().notNull(), updatedAt: timestamp('updated_at').defaultNow().notNull(), });

// lib/db/index.ts (for serverless - HTTP driver) import { neon } from '@neondatabase/serverless'; import { drizzle } from 'drizzle-orm/neon-http'; import * as schema from './schema';

const sql = neon(process.env.DATABASE_URL!); export const db = drizzle(sql, { schema });

// Usage in API route import { db } from '@/lib/db'; import { users } from '@/lib/db/schema';

export async function GET() { const allUsers = await db.select().from(users); return Response.json(allUsers); }

// lib/db/index.ts (for WebSocket - transactions) import { Pool } from '@neondatabase/serverless'; import { drizzle } from 'drizzle-orm/neon-serverless'; import * as schema from './schema';

const pool = new Pool({ connectionString: process.env.DATABASE_URL }); export const db = drizzle(pool, { schema });

// With transactions await db.transaction(async (tx) => { await tx.insert(users).values({ email: 'test@example.com' }); await tx.update(users).set({ name: 'Updated' }); });

// drizzle.config.ts import { defineConfig } from 'drizzle-kit';

export default defineConfig({ schema: './lib/db/schema.ts', out: './drizzle', dialect: 'postgresql', dbCredentials: { url: process.env.DATABASE_URL!, }, });

// Run migrations npx drizzle-kit generate npx drizzle-kit migrate

Anti_patterns

• Pattern: Using pg driver in serverless | Why: TCP connections don't work in all edge environments | Fix: Use @neondatabase/serverless driver
• Pattern: HTTP driver for transactions | Why: HTTP driver doesn't support transactions | Fix: Use WebSocket driver (Pool) for transactions

References

• https://neon.com/docs/guides/drizzle
• https://orm.drizzle.team/docs/connect-neon

Connection Pooling with PgBouncer

Neon provides built-in connection pooling via PgBouncer.

Key limits:

• Up to 10,000 concurrent connections to pooler
• Connections still consume underlying Postgres connections
• 7 connections reserved for Neon superuser

Use pooled endpoint for application, direct for migrations.

Code_example

Connection string formats

Pooled connection (for application)

Note: -pooler in hostname

postgres://user:pass@ep-cool-name-pooler.us-east-2.aws.neon.tech/neondb

Direct connection (for migrations)

Note: No -pooler

postgres://user:pass@ep-cool-name.us-east-2.aws.neon.tech/neondb

// Prisma with pooling // prisma/schema.prisma datasource db { provider = "postgresql" url = env("DATABASE_URL") // Pooled directUrl = env("DIRECT_URL") // Direct }

// Connection pool settings for high-traffic // lib/prisma.ts import { PrismaClient } from '@prisma/client';

export const prisma = new PrismaClient({ datasources: { db: { url: process.env.DATABASE_URL, }, }, // Connection pool settings // Adjust based on compute size });

// For Drizzle with connection pool import { Pool } from '@neondatabase/serverless';

const pool = new Pool({ connectionString: process.env.DATABASE_URL, max: 10, // Max connections in local pool idleTimeoutMillis: 30000, connectionTimeoutMillis: 10000, });

// Compute size connection limits // 0.25 CU: 112 connections (105 available after reserved) // 0.5 CU: 225 connections // 1 CU: 450 connections // 2 CU: 901 connections // 4 CU: 1802 connections // 8 CU: 3604 connections

Anti_patterns

• Pattern: Opening new connection per request | Why: Exhausts connection limits quickly | Fix: Use connection pooling, reuse connections
• Pattern: High max pool size in serverless | Why: Many function instances = many pools = many connections | Fix: Keep local pool size low (5-10), rely on PgBouncer

References

• https://neon.com/docs/connect/connection-pooling

Database Branching for Development

Create instant copies of your database for development, testing, and preview environments.

Branches share underlying storage (copy-on-write), making them instant and cost-effective.

Code_example

Create branch via Neon CLI

neon branches create --name feature/new-feature --parent main

Create branch from specific point in time

neon branches create --name debug/yesterday
--parent main
--timestamp "2024-01-15T10:00:00Z"

List branches

neon branches list

Get connection string for branch

neon connection-string feature/new-feature

Delete branch when done

neon branches delete feature/new-feature

// In CI/CD (GitHub Actions) // .github/workflows/preview.yml name: Preview Environment on: pull_request: types: [opened, synchronize]

jobs: create-branch: runs-on: ubuntu-latest steps: - uses: neondatabase/create-branch-action@v5 id: create-branch with: project_id: ${{ secrets.NEON_PROJECT_ID }} branch_name: preview/pr-${{ github.event.pull_request.number }} api_key: ${{ secrets.NEON_API_KEY }} username: ${{ secrets.NEON_ROLE_NAME }}

  - name: Run migrations
    env:
      DATABASE_URL: ${{ steps.create-branch.outputs.db_url_with_pooler }}
    run: npx prisma migrate deploy

  - name: Deploy to Vercel
    env:
      DATABASE_URL: ${{ steps.create-branch.outputs.db_url_with_pooler }}
    run: vercel deploy --prebuilt

// Clean