createIndex()

Creates an index on specified fields to improve query performance. Essential for production workloads.

Syntax

mongodb

db.collection.createIndex(keys, options)

Example

mongodb

// Single field index:
db.users.createIndex({ email: 1 }, { unique: true });

// Compound index:
db.posts.createIndex({ authorId: 1, createdAt: -1 });

// Text index for search:
db.articles.createIndex({ title: "text", body: "text" });

// TTL index (auto-expire documents):
db.sessions.createIndex({ expiresAt: 1 }, { expireAfterSeconds: 0 });