Filtering Data

Introduction

Filtering is the heart of every query. Building expressive, index-friendly filters separates a slow app from a fast one. Compose comparison + logical + array operators to express any condition.

Syntax reference

db.orders.find({
  status: { $in: ["paid","shipped"] },
  total:  { $gte: 100 },
  "items.sku": "A1"
});

Best practices

• Lead filters with the most selective field.
• Avoid $ne and $nin — they can't use indexes well.