Why should you care?

Slow DB becomes bottleneck no amount of Angular tuning fixes.

See it live — copy this example

Paste into your MeanVerse project (Angular + Express + MongoDB), then run with ng serve / node / mongosh as noted.

// projection — fetch only needed fields
const rows = await Account.find({ tenantId })
  .select('name balanceCents currency')
  .lean()
  .limit(100);

mongoose.connect(uri, {
  maxPoolSize: 50,
  serverSelectionTimeoutMS: 5000
});

What happened?

• select excludes heavy fields.
• lean returns plain objects — faster than Mongoose documents.
• maxPoolSize caps concurrent connections per API instance.

Practice next

1. Enable MongoDB slow query log threshold.
2. Add .select and .lean on list endpoints.
3. Review aggregation $match index usage.
4. Use cursor batchSize for CSV export stream.
5. Add readPreference secondaryPreferred for reports.

Remember

Project only fields UI needs. lean() for read-heavy JSON APIs. Pool and timeout settings matter at scale.

Black Friday catalog

Product list API returned full description HTML for 10k SKUs.

Outcome: Projection dropped payload 90%; p95 latency under 100ms.