MongoDB Indexing and Performance Optimization Practice

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🧩 MongoDB Practice Series – Indexing & Performance Challenges (Part 7)

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Welcome to Part 7 of the MongoDB Practice Series.

In this lesson, you will learn how to improve query performance using indexes.

Indexes help MongoDB find data faster, especially in large collections.

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🟢 Exercise 1: Create a Simple Index

Problem:
Create an index on the email field in the users collection.

Solution:

db.users.createIndex({ email: 1 })

Learning Goal: Improve search performance on email queries.

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🟡 Exercise 2: Find All Indexes

Problem:
Check which indexes exist in the products collection.

Solution:

db.products.getIndexes()

Learning Goal: Understand existing indexing structure.

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🟡 Exercise 3: Remove an Index

Problem:
Remove the index on the price field.

Solution:

db.products.dropIndex({ price: 1 })

Learning Goal: Learn how to manage indexes properly.

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🔵 Exercise 4: Create a Compound Index

Problem:
Create an index on both category and price fields.

Solution:

db.products.createIndex({ category: 1, price: -1 })

Learning Goal: Understand compound indexes for multi-field queries.

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🔵 Exercise 5: Optimize a Slow Query

Problem:
The following query is slow:

db.orders.find({ customerName: "Amit" })

Task:
Improve its performance.

Solution:

db.orders.createIndex({ customerName: 1 })

Learning Goal: Use indexing to speed up frequently searched fields.

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🔴 Exercise 6: Use Explain Plan

Problem:
Check how MongoDB executes a query.

Solution:

db.products.find({ price: { $gt: 1000 } }).explain("executionStats")

Learning Goal: Analyze query performance using explain.

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🚀 Mini Challenge

You have a large users collection with millions of records.

Design indexes for the following queries:

• Search users by email
• Filter users by country
• Sort users by registration date

Think carefully:

• Should you use single-field or compound indexes?
• Which field is searched most frequently?

Try designing the indexing strategy before checking any solution.

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🎯 What’s Next?

In Part 8 of the MongoDB Practice Series, we will practice:

• Real-world mini project challenges
• Complete database design scenarios
• Combining CRUD + Aggregation + Indexing

Stay tuned for the final advanced practice level!

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