Can disabling autoIndex reduce operational costs in a low‑traffic Mongoose app?

Goal: Lower operational costs for a low‑traffic Mongoose application

We want to keep data integrity while minimizing CPU, memory, and connection‑based billing on a small deployment. Two documented configuration knobs are available: mongoose.set('autoIndex', false) and the native driver’s maxPoolSize (or legacy poolSize). Setting maxPoolSize to 1 or a low value limits the number of concurrent sockets, and disabling auto‑indexing stops Mongoose from attempting to build indexes at startup.

However, the interaction between these settings and the underlying MongoDB server or managed service billing models is not fully documented. Some users report that indexes still appear to be built when the server enforces index creation, and certain cloud providers count every socket opened by the driver toward their per‑connection charges.

What is the reliable behavior of autoIndex: false across different MongoDB server versions and managed deployments? Does a maxPoolSize of 1 guarantee a single open connection on all platforms, and how does that affect provider billing? How can we verify that disabling auto‑indexing does not leave critical indexes missing in production?