Connection Pools in Mongoose | Rustcode

Understanding Connection Pools in Mongoose

Connection pooling is a technique used to maintain multiple open connections to the MongoDB server, allowing your Mongoose application to reuse existing connections efficiently and improve performance.

What is a Connection Pool?

Rather than opening and closing a new connection for every database operation, a connection pool keeps a set of connections open. This reduces connection overhead, latency, and resource consumption by reusing these connections for multiple requests.

Configuring Connection Pool Size

You can configure the maximum number of connections in the pool using the maxPoolSize option when connecting:

mongoose.connect('mongodb://localhost:27017/mydb', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  maxPoolSize: 10  // Default is 5 or 100 depending on the driver version
});

Adjusting maxPoolSize helps balance performance and resource usage based on your application's workload.

Other Pool-Related Options

minPoolSize: Minimum number of connections to keep open in the pool.
maxIdleTimeMS: Time a connection can remain idle in the pool before being closed.
waitQueueTimeoutMS: Maximum time an operation waits for an available connection from the pool.

Benefits of Using Connection Pools

Reduced latency from connection reuse.
Better resource management on the MongoDB server and client.
Improved scalability of your application.

Summary Table

Option	Description	Default
`maxPoolSize`	Maximum number of connections in the pool	5 (or 100 in recent driver versions)
`minPoolSize`	Minimum pool size maintained	0
`maxIdleTimeMS`	Idle time before closing a connection	0 (no timeout)
`waitQueueTimeoutMS`	Max time an operation waits for a connection	0 (no timeout)

Best Practices

Set maxPoolSize based on expected application load and server capacity.
Monitor connection pool usage with MongoDB monitoring tools.
Use the useUnifiedTopology option to leverage the latest server discovery and monitoring features.

Conclusion

Connection pooling is essential for building efficient and scalable Mongoose applications. Proper configuration ensures your app can handle increased load while efficiently using MongoDB resources.

Connection Pools in Mongoose