MongoDB Shell Commands

Command Categories

🔹 Database Commands

Commands for managing and inspecting databases. These are your primary tools for database-level operations, providing information and control over your MongoDB instances.

🔸 Basic Database Operations

// Show all databases
show dbs

// Switch to database (creates if doesn't exist)
use myDatabase

// Show current database
db

// Get current database name
db.getName()

// Drop current database
db.dropDatabase()

// Get database statistics
db.stats()

// Get server version
db.version()

admin      40.00 KiB
config     12.00 KiB
local      72.00 KiB
myDatabase 256.00 KiB

switched to db myDatabase
myDatabase

🔸 Database Information

// Get detailed database stats
db.stats()

// Get server status
db.serverStatus()

// Get server build info
db.serverBuildInfo()

// Get current operations
db.currentOp()

// Get profiling level
db.getProfilingLevel()

// Set profiling level (0=off, 1=slow, 2=all)
db.setProfilingLevel(1, { slowms: 100 })

🔹 Collection Commands

Manage collections within your database. Collections are groups of documents, similar to tables in relational databases, and these commands help you create, modify, and inspect them.

🔸 Collection Management

// Show all collections
show collections

// Create collection
db.createCollection("users")

// Create collection with options
db.createCollection("products", {
  capped: true,
  size: 5242880,
  max: 5000
})

// Rename collection
db.users.renameCollection("customers")

// Drop collection
db.users.drop()

// Get collection statistics
db.users.stats()

🔸 Collection Information

// Count documents in collection
db.users.countDocuments()

// Count with filter
db.users.countDocuments({ age: { $gt: 18 } })

// Get collection size
db.users.dataSize()

// Get storage size
db.users.storageSize()

// Get total index size
db.users.totalIndexSize()

// Validate collection
db.users.validate()

🔹 Index Commands

Create and manage indexes to improve query performance. Indexes are crucial for fast data retrieval, especially with large collections and complex queries.

🔸 Index Operations

// Show all indexes
db.users.getIndexes()

// Create single field index
db.users.createIndex({ email: 1 })

// Create compound index
db.users.createIndex({ lastName: 1, firstName: 1 })

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

// Create text index
db.articles.createIndex({ content: "text" })

// Drop specific index
db.users.dropIndex("email_1")

// Drop all indexes (except _id)
db.users.dropIndexes()

// Rebuild indexes
db.users.reIndex()

🔸 Index Analysis

// Explain query execution
db.users.find({ age: 25 }).explain("executionStats")

// Get index statistics
db.users.aggregate([{ $indexStats: {} }])

// Check if index is used
db.users.find({ email: "[email protected]" }).explain()

🔹 Query Commands

Advanced query operations and modifiers for precise data retrieval:

🔸 Query Modifiers

// Limit results
db.users.find().limit(10)

// Skip documents
db.users.find().skip(20)

// Sort results
db.users.find().sort({ age: -1 })

// Project specific fields
db.users.find({}, { name: 1, email: 1, _id: 0 })

// Count results
db.users.find({ age: { $gt: 18 } }).count()

// Distinct values
db.users.distinct("country")

// Find and modify
db.users.findAndModify({
  query: { name: "John" },
  update: { $set: { age: 26 } },
  new: true
})

🔸 Aggregation Commands

// Basic aggregation
db.orders.aggregate([
  { $match: { status: "completed" } },
  { $group: { _id: "$customerId", total: { $sum: "$amount" } } }
])

// Count by group
db.users.aggregate([
  { $group: { _id: "$country", count: { $sum: 1 } } }
])

// Calculate average
db.products.aggregate([
  { $group: { _id: "$category", avgPrice: { $avg: "$price" } } }
])

🔹 User Management Commands

Create and manage database users with specific roles and permissions:

// Show users
show users

// Create user
db.createUser({
  user: "appUser",
  pwd: "securePassword123",
  roles: [
    { role: "readWrite", db: "myDatabase" }
  ]
})

// Create admin user
db.createUser({
  user: "admin",
  pwd: "adminPassword123",
  roles: [
    { role: "userAdminAnyDatabase", db: "admin" },
    { role: "dbAdminAnyDatabase", db: "admin" }
  ]
})

// Update user password
db.changeUserPassword("appUser", "newPassword456")

// Grant role to user
db.grantRolesToUser("appUser", [
  { role: "dbAdmin", db: "myDatabase" }
])

// Revoke role from user
db.revokeRolesFromUser("appUser", [
  { role: "dbAdmin", db: "myDatabase" }
])

// Drop user
db.dropUser("appUser")

// Get user info
db.getUser("appUser")

🔹 Utility Commands

Helpful commands for debugging and information:

// Get help
help

// Database methods help
db.help()

// Collection methods help
db.users.help()

// Show recent logs
show log global

// Get hostname
db.hostInfo()

// Get command history
db.adminCommand({ getLog: "global" })

// Print in JSON format
printjson(db.users.findOne())

🔹 Bulk Operations

Perform multiple operations efficiently in a single batch:

// Initialize bulk operation
var bulk = db.users.initializeUnorderedBulkOp()

// Add operations
bulk.insert({ name: "Alice", age: 25 })
bulk.insert({ name: "Bob", age: 30 })
bulk.find({ name: "Charlie" }).update({ $set: { age: 35 } })
bulk.find({ age: { $lt: 18 } }).remove()

// Execute bulk operation
bulk.execute()

// Ordered bulk operation
var orderedBulk = db.users.initializeOrderedBulkOp()
orderedBulk.insert({ name: "David", age: 28 })
orderedBulk.find({ name: "Eve" }).updateOne({ $inc: { age: 1 } })
orderedBulk.execute()