Node.js Database Integration — Questions and Answers
Question 1: What is an ORM and why is it used in Node.js applications?
- Object-Relational Mapping — it lets developers interact with databases using JavaScript objects instead of raw SQL (Correct answer)
- Online Resource Manager — a tool for managing cloud resources
- Optimized Runtime Module — a performance enhancement library
- Output Rendering Mechanism — a template engine for HTML
Correct answer: Object-Relational Mapping — it lets developers interact with databases using JavaScript objects instead of raw SQL
An ORM (Object-Relational Mapping) provides a layer between the application and database, allowing developers to work with database records as JavaScript objects rather than writing raw SQL queries.
Question 2: What is connection pooling and why is it important?
- Reusing database connections instead of creating new ones for each query, improving performance (Correct answer)
- Combining multiple databases into one large pool
- Pooling connections from multiple servers to one database
- A backup strategy for database connections
Correct answer: Reusing database connections instead of creating new ones for each query, improving performance
Connection pooling maintains a cache of database connections that can be reused, avoiding the overhead of creating and destroying connections for each query, significantly improving performance.
Question 3: What is the 'N+1 query problem' in database-backed applications?
- When fetching related data requires 1 initial query plus N additional queries for each result (Correct answer)
- A limitation allowing only N+1 total queries per session
- A security vulnerability allowing injection of N+1 SQL statements
- A database design pattern using N+1 tables
Correct answer: When fetching related data requires 1 initial query plus N additional queries for each result
The N+1 problem occurs when an application executes one query to fetch N records, then executes N additional queries to fetch related data for each record, causing severe performance issues.
Question 4: What is a database migration in the context of Node.js development?
- A version-controlled script that modifies the database schema in a predictable, repeatable way (Correct answer)
- Moving a database from one server to another
- Converting a SQL database to a NoSQL database
- Backing up data before a server upgrade
Correct answer: A version-controlled script that modifies the database schema in a predictable, repeatable way
Database migrations are versioned scripts that make incremental changes to the database schema (creating tables, adding columns, etc.) in a controlled, repeatable manner that can be applied across environments.
Question 5: What is the difference between SQL and NoSQL databases in Node.js applications?
- SQL databases use structured tables with schemas; NoSQL databases use flexible document, key-value, or graph structures (Correct answer)
- SQL databases are faster; NoSQL databases are more reliable
- There is no practical difference for Node.js applications
- SQL databases only work with Java; NoSQL only works with Node.js
Correct answer: SQL databases use structured tables with schemas; NoSQL databases use flexible document, key-value, or graph structures
SQL databases (PostgreSQL, MySQL) use structured tables with predefined schemas and relationships, while NoSQL databases (MongoDB, Redis) offer flexible data models suited for unstructured or rapidly changing data.
Question 6: What is Mongoose in the Node.js ecosystem?
- An ODM (Object Document Mapper) for MongoDB that provides schema validation and data modeling (Correct answer)
- A testing framework for Node.js applications
- A task scheduler for running cron jobs
- A CSS preprocessing library for server-side rendering
Correct answer: An ODM (Object Document Mapper) for MongoDB that provides schema validation and data modeling
Mongoose is an ODM library for MongoDB that provides schema definitions, data validation, middleware hooks, and query building for MongoDB documents in Node.js applications.
Node.js Database Integration
What is an ORM and why is it used in Node.js applications?