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

// Cleanup on PR close on: pull_request: types: [closed]

jobs: delete-branch: runs-on: ubuntu-latest steps: - uses: neondatabase/delete-branch-action@v3 with: project_id: ${{ secrets.NEON_PROJECT_ID }} branch: preview/pr-${{ github.event.pull_request.number }} api_key: ${{ secrets.NEON_API_KEY }}

Anti_patterns

• Pattern: Sharing production database for development | Why: Risk of data corruption, no isolation | Fix: Create development branches from production
• Pattern: Not cleaning up old branches | Why: Accumulates storage and clutter | Fix: Auto-delete branches on PR close

References

• https://neon.com/blog/branching-with-preview-environments
• https://github.com/neondatabase/create-branch-action

Vercel Preview Environment Integration

Automatically create database branches for Vercel preview deployments. Each PR gets its own isolated database.

Two integration options:

• Vercel-Managed: Billing in Vercel, auto-setup
• Neon-Managed: Billing in Neon, more control

Code_example

Vercel-Managed Integration

1. Go to Vercel Dashboard > Storage > Create Database

2. Select Neon Postgres

3. Enable "Create a branch for each preview deployment"

4. Environment variables automatically injected

Neon-Managed Integration

1. Install from Neon Dashboard > Integrations > Vercel

2. Select Vercel project to connect

3. Enable "Create a branch for each preview deployment"

4. Optionally enable auto-delete on branch delete

// vercel.json - Add migration to build { "buildCommand": "prisma migrate deploy && next build", "framework": "nextjs" }

// Or in package.json { "scripts": { "vercel-build": "prisma generate && prisma migrate deploy && next build" } }

// Environment variables injected by integration // DATABASE_URL - Pooled connection for preview branch // DATABASE_URL_UNPOOLED - Direct connection for migrations // PGHOST, PGUSER, PGDATABASE, PGPASSWORD - Individual vars

// Prisma schema for Vercel integration datasource db { provider = "postgresql" url = env("DATABASE_URL") directUrl = env("DATABASE_URL_UNPOOLED") // Vercel variable }

// For Drizzle in Next.js on Vercel import { neon } from '@neondatabase/serverless'; import { drizzle } from 'drizzle-orm/neon-http';

// Use pooled URL for queries const sql = neon(process.env.DATABASE_URL!); export const db = drizzle(sql);

Anti_patterns

• Pattern: Same database for all previews | Why: Previews interfere with each other | Fix: Enable branch-per-preview in integration
• Pattern: Not running migrations on preview | Why: Schema mismatch between code and database | Fix: Add migrate command to build step

References

• https://neon.com/docs/guides/vercel-managed-integration
• https://neon.com/docs/guides/neon-managed-vercel-integration

Autoscaling and Cold Start Management

Neon autoscales compute resources and scales to zero.

Cold start latency: 500ms - few seconds when waking from idle. Production recommendation: Disable scale-to-zero, set minimum compute.

Code_example

Neon Console settings for production

Project Settings > Compute > Default compute size

- Set minimum to 0.5 CU or higher

- Disable "Suspend compute after inactivity"

// Handle cold starts in application // lib/db-with-retry.ts import { prisma } from './prisma';

const MAX_RETRIES = 3; const RETRY_DELAY = 1000;

export async function queryWithRetry<T>( query: () => Promise<T> ): Promise<T> { let lastError: Error | undefined;

for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) { try { return await query(); } catch (error) { lastError = error as Error;

  // Retry on connection errors (cold start)
  if (error.code === 'P1001' || error.code === 'P1002') {
    console.log(`Retry attempt ${attempt}/${MAX_RETRIES}`);
    await new Promise(r => setTimeout(r, RETRY_DELAY * attempt));
    continue;
  }

  throw error;
}

}

throw lastError; }

// Usage const users = await queryWithRetry(() => prisma.user.findMany() );

// Reduce cold start latency with SSL direct negotiation

PostgreSQL 17+ connection string

postgres://user:pass@ep-xxx-pooler.aws.neon.tech/db?sslmode=require&sslnegotiation=direct

// Keep-alive for long-running apps // lib/db-keepalive.ts import { prisma } from './prisma';

// Ping database every 4 minutes to prevent suspend const KEEPALIVE_INTERVAL = 4 * 60 * 1000;

if (process.env.NEON_KEEPALIVE === 'true') { setInterval(async () => { try { await prisma.$queryRawSELECT 1; } catch (error) { console.error('Keepalive failed:', error); } }, KEEPALIVE_INTERVAL); }

// Compute sizing recommendations // Development: 0.25 CU, scale-to-zero enabled // Staging: 0.5 CU, scale-to-zero enabled // Production: 1+ CU, scale-to-zero DISABLED // High-traffic: 2-4 CU minimum, autoscaling enabled

Anti_patterns

• Pattern: Scale-to-zero in production | Why: Cold starts add 500ms+ latency to first request | Fix: Disable scale-to-zero for production branch
• Pattern: No retry logic for cold starts | Why: First connection after idle may timeout | Fix: Add retry with exponential backoff

References

• https://neon.com/blog/scaling-serverless-postgres
• https://neon.com/docs/connect/connection-latency

Sharp Edges

Cold Start Latency After Scale-to-Zero

Severity: HIGH

Using Pooled Connection for Migrations

Severity: HIGH

Connection Pool Exhaustion in Serverless

Severity: HIGH

PgBouncer Feature Limitations

Severity: MEDIUM

Branch Storage Accumulation

Severity: MEDIUM

Reserved Connections Reduce Available Pool

Severity: LOW

HTTP Driver Doesn't Support Transactions

Severity: MEDIUM

Deleting Parent Branch Affects Children

Severity: HIGH

Schema Drift Between Branches

Severity: MEDIUM

Validation Checks

Direct Database URL in Client Code

Severity: ERROR

Direct database URLs should never be exposed to client

Message: Direct URL exposed to client. Only pooled URLs for server-side use.

Hardcoded Database Connection String

Severity: ERROR

Connection strings should use environment variables

Message: Hardcoded connection string. Use environment variables.

Missing SSL Mode in Connection String

Severity: WARNING

Neon requires SSL connections

Message: Missing sslmode=require. Add to connection string.

Prisma Missing directUrl for Migrations

Severity: ERROR

Prisma needs directUrl for migrations through PgBouncer

Message: Using pooled URL without directUrl. Migrations will fail.

Prisma directUrl Points to Pooler

Severity: ERROR

directUrl should be non-pooled connection

Message: directUrl points to pooler. Use non-pooled endpoint for migrations.

High Pool Size in Serverless Function

Severity: WARNING

High pool sizes exhaust connections with many function instances

Message: Pool size too high for serverless. Use max: 5-10.

Creating New Client Per Request

Severity: WARNING

Creating new clients per request wastes connections

Message: Creating client per request. Use connection pool or neon() driver.

Branch Creation Without Cleanup Strategy

Severity: WARNING

Branches should have cleanup automation

Message: Creating branch without cleanup. Add delete-branch-action to PR close.

Scale-to-Zero Enabled on Production

Severity: WARNING

Scale-to-zero adds latency in production

Message: Scale-to-zero on production. Disable for low-latency.

HTTP Driver Used for Transactions

Severity: ERROR

neon() HTTP driver doesn't support transactions

Message: HTTP driver with transaction. Use Pool from @neondatabase/serverless.

Collaboration

Delegation Triggers

• user needs authentication -> clerk-auth (User table with clerkId column)
• user needs caching -> redis-specialist (Query caching, session storage)
• user needs search -> algolia-search (Full-text search beyond Postgres capabilities)
• user needs analytics -> segment-cdp (Track database events, user actions)
• user needs deployment -> vercel-deployment (Environment variables, preview databases)

When to Use

• User mentions or implies: neon database
• User mentions or implies: serverless postgres
• User mentions or implies: database branching
• User mentions or implies: neon postgres
• User mentions or implies: postgres serverless
• User mentions or implies: connection pooling
• User mentions or implies: preview environments
• User mentions or implies: database per preview

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.