System-Design-Question

feat: Add mock interview, system design, and coding patterns features

Category: system_design Date: 2026-03-31

Problem Statement:

Implement a system to support the following features:

1. Mock Interviews: Allow users to practice mock interviews with a timer and ratings system.
2. System Design: Provide a platform for users to design and practice system design interviews with a rating system.
3. Coding Patterns: Offer a library of commonly used coding patterns with explanations and examples.

Requirements:

Functional Requirements:

1. User authentication and authorization
2. User profile management (e.g., display ratings, interview history)
3. Mock interview creation and management
4. System design interview creation and management
5. Coding pattern library with search and filter functionality
6. Rating system for mock interviews and system design interviews

Non-Functional Requirements:

1. Scalability: Handle a large number of users and interviews
2. Availability: Ensure high uptime and minimize downtime
3. Security: Protect user data and prevent unauthorized access
4. Performance: Respond to user requests within 2 seconds
5. Reliability: Minimize errors and data inconsistencies

High-Level Architecture:

1. Frontend: Use a modern web framework (e.g., React, Angular) for user interface and client-side logic
2. Backend: Design a RESTful API using a language like Node.js, Python, or Java for server-side logic and API interactions
3. Database: Utilize a relational database management system (RDBMS) like MySQL or PostgreSQL for storing user data, interview metadata, and ratings
4. Storage: Use a cloud-based object storage service (e.g., AWS S3) for storing coding pattern resources and interview recordings

Database Design:

1. Users: Store user information in a table with columns for id, username, email, password, and ratings
2. Interviews: Create a table for mock interviews and system design interviews with columns for id, title, description, rating, and user_id
3. Ratings: Store ratings for mock interviews and system design interviews in a separate table with columns for id, rating, user_id, and interview_id
4. Coding Patterns: Store coding pattern metadata in a table with columns for id, name, description, and resource

Scaling Strategy:

1. Horizontal Scaling: Use a load balancer to distribute traffic across multiple instances of the application
2. Vertical Scaling: Increase the power of individual instances as the load increases
3. Database Scaling: Use a cloud-based RDBMS that supports horizontal scaling and automatic failover
4. Caching: Implement caching using a service like Redis or Memcached to reduce database queries

Bottlenecks:

1. Database Queries: Optimize database queries to reduce latency and improve performance
2. Network Latency: Use a content delivery network (CDN) to reduce network latency and improve responsiveness
3. User Authentication: Implement a robust authentication system to prevent unauthorized access

Trade-offs:

1. Complexity: Balance complexity with maintainability and scalability
2. Performance: Prioritize performance over other non-functional requirements
3. Security: Ensure security is a top priority and implement robust measures to protect user data

Solution:

The solution follows the First Principle of System Design: “A good system is one that balances simplicity, scalability, and performance.”

1. Simplify: Break down the problem into smaller components and focus on each component’s simplicity
2. Scale: Design the system to scale horizontally and vertically to handle increasing traffic and loads
3. Perform: Optimize database queries, caching, and network latency to ensure fast and responsive performance

Example Code:

// Node.js example using Express.js for the RESTful API
const express = require('express');
const app = express();
const mysql = require('mysql');

// Connect to the database
const db = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'password',
  database: 'database'
});

// Define API endpoints for mock interviews and system design interviews
app.get('/mock-interviews', (req, res) => {
  db.query('SELECT * FROM interviews WHERE type = "mock"', (err, results) => {
    if (err) {
      res.status(500).send({ message: 'Error fetching mock interviews' });
    } else {
      res.send(results);
    }
  });
});

app.get('/system-design-interviews', (req, res) => {
  db.query('SELECT * FROM interviews WHERE type = "system-design"', (err, results) => {
    if (err) {
      res.status(500).send({ message: 'Error fetching system design interviews' });
    } else {
      res.send(results);
    }
  });
});

// Start the server
const port = 3000;
app.listen(port, () => {
  console.log(`Server started on port ${port}`);
});

This example demonstrates a basic RESTful API using Express.js and Node.js to handle API requests for mock interviews and system design interviews. The API connects to a MySQL database to retrieve interview data.

Learning Links:

1. RESTful API design
2. System design principles
3. Database design
4. Scalability and performance
5. Node.js and Express.js tutorials

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