MongoDB Cheat Sheet

MongoDB cheat sheet with real commands and snippets for setup, core workflows, debugging, and production-safe automation patterns. If you are working across tools, pair this with the GraphQL Cheat Sheet and Redis Cheat Sheet.

Setup and Connection

Goal: Connect to database shell or endpoint

# Run connection or version command
mongosh

# Run connection or version command
mongosh "mongodb://localhost:27017/app"

# Run connection or version command
mongosh --version

Schema and Data Modeling

Goal: Create a table/index/schema foundation

// Insert sample document with nested fields
db.users.insertOne({
  email: 'user@example.com',
  profile: { name: 'Rem', role: 'admin' },
  createdAt: new Date()
});

Core Queries and Mutations

Goal: Run practical read/write operations

// Query by nested field and project selected keys
db.users.find(
  { 'profile.role': 'admin' },
  { email: 1, 'profile.name': 1, _id: 0 }
);

Performance and Optimization

Goal: Add indexes and inspect query plans

// Create index and inspect usage plan
db.users.createIndex({ email: 1 }, { unique: true });
db.users.find({ email: 'user@example.com' }).explain('executionStats');

Automation and Backups

Goal: Create backup and restore routines

# Export data snapshot before risky migrations
pg_dump "$DATABASE_URL" > backup.sql || mysqldump appdb > backup.sql || true

# Compress backup artifact for storage
gzip -f backup.sql || true

# Verify backup file exists and has content
ls -lh backup.sql.gz || ls -lh backup.sql

Debugging and Troubleshooting

Goal: Inspect slow-query symptoms

# Check active connections/sessions
psql -c "SELECT now();" || mysql -e "SELECT NOW();" || true

# Inspect query plans for heavy statements
psql -c "EXPLAIN SELECT 1;" || mysql -e "EXPLAIN SELECT 1;" || true

# Search migration files for destructive statements
rg "DROP TABLE|TRUNCATE|DELETE FROM" prisma migrations sql -n

Common Gotchas

• Use transactions for multi-step MongoDB data changes that must stay consistent.
• Create indexes for frequent WHERE and JOIN columns, then verify with query plans.
• Back up production data before schema migrations.
• Separate read-only credentials from write credentials in app environments.
• Monitor connection pool limits to avoid timeout spikes under load.

Related Sheets

• GraphQL Cheat Sheet — daily GraphQL commands and production-ready examples.
• Redis Cheat Sheet — cache and queue operations.
• Elasticsearch Cheat Sheet — daily Elasticsearch commands and production-ready examples.