Blog/Databases

MongoDB 2026: When to Use Document Database and How to Start

SynfraCore·March 2026·8 min read

When MongoDB Makes Sense

Use when: data structure varies between documents, you need nested objects without JOINs, or data is document-like by nature (articles, user profiles with variable fields).

Do NOT use when: data has clear relationships benefiting from JOINs, you need ACID transactions across multiple collections, or you are unsure — default to PostgreSQL.

CRUD Operations

javascript

const users = db.collection('users');
// Insert
await users.insertOne({ name: 'Alice', tags: ['admin'], address: { city: 'Chennai' } });
// Query nested fields
const result = await users.find({ 'address.city': 'Chennai' }).toArray();
// Update with operators
await users.updateOne(
  { name: 'Alice' },
  { $set: { 'address.city': 'Mumbai' }, $push: { tags: 'superadmin' } }
);

Aggregation Pipeline

javascript

const result = await orders.aggregate([
  { $match: { date: { $gte: new Date('2026-01-01') } } },
  { $group: { _id: '$status', count: { $sum: 1 }, avg: { $avg: '$amount' } } },
  { $sort: { count: -1 } }
]).toArray();

Common Anti-Patterns

•Unbounded arrays (16MB document limit)

•Using $lookup everywhere (if you JOIN constantly, use PostgreSQL)

•Missing indexes (MongoDB scans without them, same as SQL)

See MongoDB Academy.

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