feat: new library System Design Interview Props
Category: system_design
Date: 2026-04-03
System Design Interview Props: New Library
Problem Statement: Design a system for managing library props, including catalogs, book availability, and user checkouts. The system should be highly scalable, fault-tolerant, and provide a seamless user experience.
Requirements:
Functional Requirements:
- User: View available books, check out books, return books, and view their check-out history.
- Librarian: Manage book catalogs, update book availability, and view user check-out history.
- Admin: View system-wide statistics, manage user accounts, and configure system settings.
Non-Functional Requirements:
- Scalability: Handle a large number of users and books.
- High Availability: Ensure the system is always accessible.
- Consistency: Ensure data consistency across all nodes.
- Performance: Respond to user requests within 2 seconds.
High-Level Architecture:
- Web Interface: Built using a web framework (e.g., React, Angular) for user and librarian interfaces.
- API Gateway: Handles incoming requests, authenticates users, and routes requests to the appropriate services.
- Catalog Service: Responsible for managing book catalogs, book availability, and user check-out history.
- User Service: Handles user account management, check-out history, and user preferences.
- Database: Stores catalog data, user data, and system-wide statistics.
Database Design:
- Entity-Attribute-Value (EAV) Model: Stores catalog data, user data, and system-wide statistics in an EAV model for flexibility and scalability.
- Database Schema:
- Catalog Table: stores book information (ISBN, title, author, etc.).
- Availability Table: stores book availability status (checked out, available, etc.).
- Check-out History Table: stores user check-out history.
Scaling Strategy:
- Horizontal Scaling: Add more instances of each service to handle increased load.
- Load Balancing: Distribute incoming traffic across multiple instances.
- Caching: Implement caching at the API gateway and services to reduce database queries.
Bottlenecks:
- Database Queries: Frequent database queries can lead to performance issues.
- High Traffic: Increased traffic can lead to system overload.
- Data Consistency: Ensuring data consistency across all nodes can be challenging.
Trade-offs:
- Scalability vs. Performance: Adding more instances can improve scalability but may compromise performance.
- Caching vs. Data Consistency: Implementing caching can improve performance but may compromise data consistency.
Solution using the First Principle of System Design:
The first principle of system design is to “Keep it simple, stupid” (KISS). The solution should be easy to understand, maintain, and scale.
Solution Overview:
- Use a simple and intuitive web interface for user and librarian interactions.
- Implement a lightweight API gateway to handle incoming requests and authenticate users.
- Use a scalable database design, such as EAV, to store catalog data, user data, and system-wide statistics.
- Implement horizontal scaling, load balancing, and caching to handle increased load and improve performance.
Implementation Steps:
- Design and implement the web interface using a web framework (e.g., React, Angular).
- Implement the API gateway using a lightweight framework (e.g., Flask, Express).
- Design and implement the catalog service, user service, and database schema.
- Implement horizontal scaling, load balancing, and caching.
Learning Links: