Go Mongodb Index

In this tutorial, you'll learn about MongoDB Go Driver: Index Creation. We cover key concepts, practical examples, and best practices.

MongoDB indexes -- Create database indexes using the Go driver's IndexView for query performance.

The Problem

Without indexes, MongoDB performs collection scans. Use collection.Indexes().CreateOne() to create single, compound, or unique indexes.

Wrong

collection.Find(ctx, bson.M{"email": "alice@example.com"})

Output:

// Slow! Collection scan on all documents

Right

indexModel := mongo.IndexModel{
    Keys: bson.D{{"email", 1}},
    Options: options.Index().SetUnique(true).SetBackground(true),
}
name, err := collection.Indexes().CreateOne(ctx, indexModel)

Output:

// Fast query using email index

Prevention

• Create indexes for frequent query fields
• Use compound indexes for multi-field queries
• Use SetUnique for unique constraints
• Use SetBackground to avoid blocking
• Use CreateMany for multiple indexes

Common Mistakes with mongodb index

1. Mixing let bindings with <- bindings in do notation, producing type errors
2. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors
3. Non-exhaustive pattern matches that compile with warnings then crash at runtime

These mistakes appear frequently in real-world GO code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

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