sys-design.tar.gz

basic

System design interviews play a vital role in hiring software engineers and managers. These interviews test the ability of the candidate to solve problems under different constraints. A candidate’s performance in a system design interview is a significant factor in deciding the hire/no-hire decisions and the level assigned to the incoming candidate.

In this course, you’ll go through a miniature form of our primary course on system design: Grokking Modern System Design Interview for Engineers & Managers. This crash course aims to give you an overall gist of the system designing process using short, easy-to-digest problems. Each design problem of the course can be completed in about 15 minutes, giving you the flexibility to include them in your jam-packed schedules.

System Design Interview Prep Crash Course

## What is a newsfeed?

A **newsfeed** of any social media platform (like Twitter, Facebook, and Instagram) is a list of stories generated by entities that a user follows. It contains text, images, videos, and other activities, such as likes, comments, shares, advertisements, and many more. This list is continuously updated and presented to the relevant users on the user’s home page. Similarly, a newsfeed system also displays the newsfeed to users from friends, followers, groups, and other pages, including a user’s own posts.

## Requirements
### Functional requirements
* **Newsfeed generation:** The system will generate newsfeeds from pages, groups, friends, and followers that a user follows and must effectively curate the content by selecting and ranking it to decide which items (from many) should be displayed to the user first.

* **Newsfeed contents:** The newsfeed may contain text, images, and videos.
* **Newsfeed display:** The system should affix new incoming posts to the newsfeed for all active users based on some ranking mechanism. Once ranked, we show content to a user with higher-ranked content first.

### Non-functional requirements
* **Scalability:** Our proposed system should be highly scalable to support the ever-increasing number of users on any platform, such as Twitter, Facebook, and Instagram. 
* **Fault tolerance:** The system should be handling a large amount of data; therefore, partition tolerance (system availability in the event of network failure between the system’s components) is necessary.  
* **Availability:** The service must be highly available to keep the users engaged with the platform. The system can compromise strong consistency for availability and fault tolerance, according to the #key# PACELC theorem: The PACELC theorem is an extension of the CAP theorem that states, in the event of a network partition, we should choose between availability or consistency. Otherwise, choose between latency and consistency. #key#.

* **Low latency:** The system should provide newsfeeds in real-time. Therefore, the maximum latency should not be greater than two seconds.





# What is a newsfeed?

A **newsfeed** of any social media platform (like Twitter, Facebook, and Instagram) is a list of stories generated by entities that a user follows. It contains text, images, videos, and other activities, such as likes, comments, shares, advertisements, and many more. This list is continuously updated and presented to the relevant users on the user’s home page. Similarly, a newsfeed system also displays the newsfeed to users from friends, followers, groups, and other pages, including a user’s own posts.

# Requirements
## Functional requirements
* **Newsfeed generation:** The system will generate newsfeeds from pages, groups, friends, and followers that a user follows and must effectively curate the content by selecting and ranking it to decide which items (from many) should be displayed to the user first.

* **Newsfeed contents:** The newsfeed may contain text, images, and videos.
* **Newsfeed display:** The system should affix new incoming posts to the newsfeed for all active users based on some ranking mechanism. Once ranked, we show content to a user with higher-ranked content first.

## Non-functional requirements
* **Scalability:** Our proposed system should be highly scalable to support the ever-increasing number of users on any platform, such as Twitter, Facebook, and Instagram. 
* **Fault tolerance:** The system should be handling a large amount of data; therefore, partition tolerance (system availability in the event of network failure between the system’s components) is necessary.  
* **Availability:** The service must be highly available to keep the users engaged with the platform. The system can compromise strong consistency for availability and fault tolerance, according to the #key# PACELC theorem: The PACELC theorem is an extension of the CAP theorem that states, in the event of a network partition, we should choose between availability or consistency. Otherwise, choose between latency and consistency. #key#.

* **Low latency:** The system should provide newsfeeds in real-time. Therefore, the maximum latency should not be greater than two seconds.





Introduction

Elementary Design Problems

Advanced Design Problems

Concluding Remarks

Design a Newsfeed

What is a newsfeed?

Requirements

Functional requirements

Non-functional requirements