Connection pooling for serverless in NextJS - Mini Project: Build & Apply

Connection pooling for serverless in Next.js

📖 Scenario: You are building a Next.js API route that connects to a PostgreSQL database. Since serverless functions start fresh on each request, you want to reuse database connections efficiently to avoid opening too many connections.This technique is called connection pooling and helps your app stay fast and stable.

🎯 Goal: Create a Next.js API route that uses a connection pool to query the database. You will set up the pool, configure it, write the query logic, and export the handler.

📋 What You'll Learn

Use the pg package to create a connection pool

Configure the pool with a max of 5 connections

Write an async function to query the database for all users

Export a Next.js API route handler that returns the users as JSON

💡 Why This Matters

🌍 Real World

Serverless functions like Next.js API routes start fresh on each request. Without connection pooling, each request opens a new database connection, which can overload the database. Connection pooling reuses connections, improving performance and stability.

💼 Career

Understanding connection pooling is important for backend and full-stack developers working with serverless platforms and databases. It helps build scalable, efficient APIs.

1

Set up the connection pool

Import Pool from pg and create a connection pool called pool with max set to 5.

NextJS

import { Pool } from 'pg'

// Your code here

Need a hint?

Use new Pool({ max: 5 }) to create the pool.

2

Configure the database connection string

Add a connectionString property to the pool configuration with the value process.env.DATABASE_URL.

NextJS

import { Pool } from 'pg'

const pool = new Pool({
  max: 5,
  // Your code here
})

Need a hint?

Use connectionString: process.env.DATABASE_URL inside the pool config.

3

Write the query function

Create an async function called getUsers that uses pool.query to select all rows from the users table and returns result.rows.

NextJS

import { Pool } from 'pg'

const pool = new Pool({
  max: 5,
  connectionString: process.env.DATABASE_URL
})

// Your code here

Need a hint?

Use await pool.query('SELECT * FROM users') and return result.rows.

4

Export the API route handler

Export an async default function called handler that calls getUsers, then returns a JSON response with status 200 and the users array.

NextJS

import { Pool } from 'pg'

const pool = new Pool({
  max: 5,
  connectionString: process.env.DATABASE_URL
})

async function getUsers() {
  const result = await pool.query('SELECT * FROM users')
  return result.rows
}

// Your code here

Need a hint?

Use export default async function handler(req, res) and respond with res.status(200).json({ users }).