MongoDB Query Optimization: A Deep Dive

Database performance is often the bottleneck in MERN applications. Here's how we systematically optimized our MongoDB queries.

Indexing Strategy

We started with explain() on every query taking over 100ms. The results were eye-opening — 60% of slow queries were doing collection scans.

Aggregation Pipeline Optimization

Moving filtering stages earlier in the pipeline and using $match before $lookup reduced our aggregation times by 75%.

Connection Pooling

Proper connection pool configuration alone saved us from connection timeout errors during traffic spikes.