To manage user sign-ups effectively with Clerk in a Next.js application, utilize middleware to intercept requests. Instead of querying the database on every request, leverage Clerk's built-in capabilities to differentiate between sign-up and regular requests. This approach minimizes database calls and optimizes performance.

// middleware.js
import { withClerkMiddleware } from '@clerk/nextjs/middleware';

const middleware = withClerkMiddleware((req, res, next) => {
  const { userId } = req.auth;
  // Check if the user is signing up
  if (req.method === 'POST' && req.url === '/api/signup') {
    // Logic to add user to the database
    addUserToDatabase(userId);
  }
  next();
});

export default middleware;

// Function to add user to the database
async function addUserToDatabase(userId) {
  // Implement your database logic here to add a new user
  console.log(`Adding user with ID: ${userId}`);
  // Example: await db.users.insert({ id: userId });
}