Best practice for handling database connections in Next.js API routes with MySQL?

[codiebyheaart]

Summary

I'm building a Next.js app with MySQL backend. I'm seeing connection pool exhaustion after ~50 API calls.

My questions:

1. Should I create a new connection for each API route call?
2. How to implement connection pooling properly?
3. Where to initialize the database client (global vs per-request)?

Current approach feels inefficient and causing performance issues.

Additional information

**Setup:**
- Next.js 14.0.4
- MySQL 8.0
- Using mysql2 package
- Deployed on Vercel

**Current Code Pattern:**

// app/api/users/route.js
export async function GET() {
  const connection = await mysql.createConnection(config); // New connection every time?
  const [rows] = await connection.execute('SELECT * FROM users');
  await connection.end();
  return Response.json(rows);
}


**Issues:**
- Slow API responses after multiple requests
- "Too many connections" error
- Unsure about Vercel's serverless limitations

Any recommendations for production-ready patterns?

Example

No response

[icyJoseph]

Yeah, well depends, but mostly the right thing to do should be:

• https://sidorares.github.io/node-mysql2/docs#using-connection-pools

If you have fluid compute on, an instance may be used to serve many requests, and each new incoming one creates a connection as you have it.

Then you can execute the query against the pool, right?

I think before fluid compute you'd create a connection, query, close and serve the data.

And where to place it, well a lib/db-pool file, where you export the pool from. I think in dev mode you might want to save the pool to globalThis: https://github.com/vercel/next.js/blob/canary/examples/with-mongodb/lib/mongodb.ts

That example creates a new mongo client in prod, you'd create a pool rather.