MongoDB Query Cookbook

Leading document-oriented NoSQL database managing schema-less JSON-like BSON objects. 10 production-tested query recipes ready to copy and execute.

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1. Multi-Stage Aggregation Pipeline ($match & $group)

Filter, group, and calculate totals over document collections.

db.orders.aggregate([
  { $match: { status: "completed" } },
  { $group: {
      _id: "$customerId",
      totalSpent: { $sum: "$amount" },
      orderCount: { $sum: 1 }
  }},
  { $sort: { totalSpent: -1 } }
]);

#aggregation#pipeline#group

2. Left Outer Join Collections ($lookup)

Join related documents from secondary collection.

db.orders.aggregate([
  { $lookup: {
      from: "users",
      localField: "userId",
      foreignField: "_id",
      as: "userInfo"
  }},
  { $unwind: "$userInfo" }
]);

#lookup#join#unwind

3. Update Document with Upsert Option

Modify matching document or insert new object if missing.

db.users.updateOne(
  { email: "alex@example.com" },
  { 
    $set: { name: "Alex", lastActive: new Date() },
    $inc: { loginCount: 1 }
  },
  { upsert: true }
);

#update#upsert#crud

4. Text Search Index & Query

Create text index and run natural language searches.

db.articles.createIndex({ title: "text", content: "text" });

db.articles.find(
  { $text: { $search: "database query optimization" } },
  { score: { $meta: "textScore" } }
).sort({ score: { $meta: "textScore" } });

#text#search#index

5. Geospatial Near Location Search ($near)

Find documents near geographical coordinates.

db.places.createIndex({ location: "2dsphere" });

db.places.find({
  location: {
    $near: {
      $geometry: { type: "Point", coordinates: [ -73.9667, 40.78 ] },
      $maxDistance: 5000
    }
  }
});

#geo#2dsphere#spatial

6. Push Element to Array Field ($push)

Add unique element to document array field.

db.users.updateOne(
  { _id: ObjectId("60d5ec49f1a2c80015f8e123") },
  { $addToSet: { tags: "premium" } }
);

#array#push#update

7. Build Compound Index Background

Create multi-field index without locking write operations.

db.logs.createIndex(
  { status: 1, timestamp: -1 },
  { background: true }
);

#index#compound#performance

8. Auto-Expire Documents with TTL Index

Set automatic document deletion after expiration interval.

db.sessions.createIndex(
  { createdAt: 1 },
  { expireAfterSeconds: 3600 }
);

#ttl#index#expire

9. Enforce Document JSON Schema

Add strict structural validation rules to collection.

db.createCollection("products", {
  validator: {
    $jsonSchema: {
      bsonType: "object",
      required: ["name", "price"],
      properties: {
        name: { bsonType: "string" },
        price: { bsonType: "double", minimum: 0 }
      }
    }
  }
});

#schema#validation#ddl

10. Inspect Aggregation Plan Execution

Inspect query execution statistics using explain().

db.orders.explain("executionStats").find({ status: "pending" });

#explain#performance#stats

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