Does Fastify Work With PostgreSQL?
Fastify and PostgreSQL work together seamlessly; use a PostgreSQL client library like pg or Prisma to query your database from Fastify routes.
Quick Facts
How Fastify Works With PostgreSQL
Fastify doesn't include database drivers by default, but integrating PostgreSQL is straightforward using community packages. The most common approach is using the `pg` library directly or an ORM like Prisma, TypeORM, or Sequelize. Fastify's plugin system makes it easy to register a database connection pool at startup, ensuring connections are reused efficiently and properly closed on shutdown. The asynchronous nature of Fastify routes pairs well with PostgreSQL's async query execution, allowing you to handle database operations without blocking. Developers typically create a plugin that initializes the connection pool and makes it available via `fastify.db`, following Fastify's decorator pattern for clean architecture. Connection pooling is critical—Fastify's high throughput can overwhelm PostgreSQL if you don't properly manage concurrent connections, so configuring appropriate pool sizes (typically 10-20 connections) is essential.
Best Use Cases
Quick Setup
npm install fastify pg && npm install --save-dev @types/pgimport Fastify from 'fastify';
import { Pool } from 'pg';
const fastify = Fastify();
const pool = new Pool({
connectionString: process.env.DATABASE_URL,
max: 20,
});
fastify.decorate('db', pool);
fastify.get('/users/:id', async (request, reply) => {
const { id } = request.params;
const result = await fastify.db.query(
'SELECT * FROM users WHERE id = $1',
[id]
);
return result.rows[0] || null;
});
fastify.listen({ port: 3000 }, (err) => {
if (err) throw err;
console.log('Server running on port 3000');
});Known Issues & Gotchas
Connection pool exhaustion under high load if pool size isn't configured correctly
Fix: Set appropriate pool.max (usually 20-30) and monitor active connections. Use connection poolers like PgBouncer for production at scale.
Unhandled promise rejections from failed queries crashing the server
Fix: Always use try-catch or .catch() in async route handlers; consider using Fastify's error handler plugin for consistent error responses.
N+1 query problems when fetching related data without proper joins
Fix: Use SQL joins or an ORM with eager loading capabilities to fetch related records efficiently.
Prepared statement parameter handling differences between libraries
Fix: Use parameterized queries consistently (e.g., $1, $2 for pg library) to prevent SQL injection.
Alternatives
- •Express.js with PostgreSQL (more mature ecosystem, slower performance)
- •NestJS with TypeORM and PostgreSQL (more opinionated framework, better for larger teams)
- •Hono with PostgreSQL (lightweight alternative, growing ecosystem)
Resources
Related Compatibility Guides
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