In Next.js, each API route runs as a separate serverless function or lambda function. This is different from a traditional Express.js application, where the server runs continuously and can maintain a persistent database connection. In a serverless architecture like the one used by Next.js API routes, each request is handled by a separate instance that may be created and destroyed independently. Therefore, you need to ensure that a database connection is established for each API route handler.
Why Connect to the Database in Each Route in Next.js?
Serverless Architecture:
Next.js API routes run in a serverless environment, such as Vercel or AWS Lambda. Each route handler may be invoked in isolation, with no shared state or persistent connections between invocations.
In serverless environments, there is no guarantee that a previously established database connection will persist between requests.
Ensuring Availability:
- Each invocation of a serverless function must ensure that it has a valid database connection to perform its operations. This is why
dbConnectis called within each route handler.
- Each invocation of a serverless function must ensure that it has a valid database connection to perform its operations. This is why
Optimized Connection Management in Next.js
Despite the need to call dbConnect in each route, you can still optimize the connection process to minimize overhead:
Connection Pooling:
- Mongoose and most database drivers support connection pooling. Once a connection pool is created, the driver manages reusing connections efficiently.
Caching the Connection:
- You can cache the database connection to reuse it within the same invocation context. This reduces the overhead of reconnecting to the database if the function is "warmed" (reused by the platform for multiple requests).