Firestore Best Practices

Query Optimization

Filters & Limits

// ❌ BAD: Fetch all, filter in JS
const all = await customersRef.get();
const active = all.docs.filter(d => d.data().status === 'active');

// ✅ GOOD: Filter in query
const active = await customersRef
  .where('status', '==', 'active')
  .where('shopId', '==', shopId)
  .limit(100)
  .get();