Code
mongodb
// Single field index
db.users.createIndex({ email: 1 }, { unique: true });
// Compound index
db.orders.createIndex({ customerId: 1, createdAt: -1 });
// Text index
db.posts.createIndex({ title: "text", body: "text" });
db.posts.find({ $text: { $search: "mongodb tutorial" } });
// List and drop
db.orders.getIndexes();
db.orders.dropIndex("customerId_1_createdAt_-1");
// Explain plan
db.orders.find({ customerId: "c1" }).explain("executionStats");