25 Essential MongoDB Commands for Efficient Data Management

MongoDB, a popular NoSQL database, offers a comprehensive set of commands for managing data efficiently. This blog post will delve into the 25 most commonly used MongoDB commands, providing detailed descriptions and code example. By mastering these commands, you can unlock the full potential of MongoDB and optimize your database operations.

1. db.collection.find()

Purpose: retrieves documents matching a specified query.

Code Example:

db.collection.find({ name: "John" })

2. db.collection.findOne()

Purpose: retrieves a single document matching a specified query.

Code Example:

db.collection.findOne({ _id: ObjectId("5f923367204e6e03263068fe") })

3. db.collection.insertOne()

Purpose: inserts a single document into the collection.

Code Example:

db.collection.insertOne({ name: "Jane", age: 25 })

4. db.collection.insertMany()

Purpose: inserts multiple documents into the collection.

Code Example:

db.collection.insertMany([
  { name: "Bob", age: 30 },
  { name: "Alice", age: 22 }
])

5. db.collection.updateOne()

Purpose: updates a single document matching a specified query.

Code Example:

db.collection.updateOne({ name: "John" }, { $set: { age: 35 } })

6. db.collection.updateMany()

Purpose: updates multiple documents matching a specified query.

Code Example:

db.collection.updateMany({ age: { $gt: 30 } }, { $inc: { age: 1 } })

7. db.collection.deleteOne()

Purpose: deletes a single document matching a specified query.

Code Example:

db.collection.deleteOne({ name: "John" })

8. db.collection.deleteMany()

Purpose: deletes multiple documents matching a specified query.

Code Example:

db.collection.deleteMany({ age: { $lt: 25 } })

9. db.collection.count()

Purpose: returns the number of documents in the collection.

Code Example:

db.collection.count()

10. db.collection.findAndModify()

Purpose: performs a combination of find and update or find and delete operations.

Code Example:

db.collection.findAndModify({ query: { name: "John" }, update: { $set: { age: 35 } }, new: true })

11. db.collection.aggregate()

Purpose: performs data aggregation operations on the collection, such as grouping, sorting, and computing statistics.

Code Example:


db.collection.aggregate([
  { $group: { _id: "$category", total: { $sum: "$price" } } }
])

12. db.collection.createIndex()

Purpose: creates an index on a specific field or set of fields in the collection to improve query performance.

Code Example:

db.collection.createIndex({ name: 1 })

13. db.collection.dropIndex()

Purpose: drops an index from the collection.

Code Example:

db.collection.dropIndex("name_1")

14. db.collection.ensureIndex()

Purpose: ensures that an index exists on a specific field or set of fields in the collection.

Code Example:

db.collection.ensureIndex({ name: 1 })

15. db.collection.explain()

Purpose: provides information about how a query was executed and optimized by MongoDB.

Code Example:

db.collection.explain().find({ name: "John" })

16. db.collection.stats()

Purpose: returns statistical information about the collection, such as the number of documents, size, and index usage.

Code Example:

db.collection.stats()

17. db.collection.drop()

Purpose: drops the entire collection, including all its documents and indexes.

Code Example:

db.collection.drop()

18. db.collection.rename()

Purpose: renames the collection to a specified new name.

Code Example:

db.collection.rename("new_collection")

19. db.collection.validate()

Purpose: checks the integrity of the collection and its indexes.

Code Example:

db.collection.validate()

20. db.collection.repair()

Purpose: repairs any inconsistencies or corruptions in the collection.

Code Example:

db.collection.repair()

21. db.collection.compact()

Purpose: compacts the collection to reclaim unused space.

Code Example:

db.collection.compact()

22. db.collection.distinct()

Purpose: returns a distinct set of values for a specified field in the collection.

Code Example:

db.collection.distinct("name")

23. db.collection.parallelCollectionScan()

Purpose: performs a parallel scan of the collection, dividing it into chunks and processing them simultaneously.

Code Example:

db.collection.parallelCollectionScan().find({ name: "John" })

24. db.collection.getIndexes()

Purpose: returns a list of all indexes in the collection.

Code Example:

db.collection.getIndexes()

25. db.collection.mapReduce()

Purpose: performs a map-reduce operation on the collection, allowing for custom data processing and aggregation.

Code Example:


db.collection.mapReduce(
  function() { emit(this.category, this.price); },
  function(key, values) { return Array.sum(values); },
  { out: "result_collection" }
)

Conclusion

Mastering these 25 MongoDB commands is essential for efficient data management. By leveraging their capabilities, you can perform complex queries, update and insert data, create and manage indexes and optimize performance. MongoDB's flexibility and scalability make it an ideal choice for storing and manipulating large datasets. Embrace these commands and unlock the full potential of MongoDB for your next project.

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