System requirements


Functional:

  • User should be able to view their feed
  • the user feed will be paginated
  • User should be able to create tweets
  • User should be able to delete tweets
  • user should be able to favorite tweets



Non-Functional:

  • should be able to process 10 million reads a day
  • should be able to process 100k writes per day
  • updates to the timelines should be instant
  • The system should account for burst traffic
  • high availability and low latency. We can sacrifice consistency to ensure that availability and latency are met.




Capacity estimation






API design

  • user login/logout API
  • fetchUserFeed API - will need pagination token
  • createTweet API
  • FavoriteTweet API
  • deleteTweet API





Database design

user table

  • PK: id
  • userName
  • created_at
  • is_deleted flag
  • GSI: first and last name


Follower Table

  • pk: user_ID #shard
  • sk: follower_user_id


tweets table

  • PK: user_id
  • SK: user_id:tweetId
  • tweetId
  • created_at
  • is_deleted


favorite Table

  • pk: tweet_id
  • sk: user_id
  • time_stamp





High-level design

You should identify enough components that are needed to solve the actual problem from end to end. Also remember to draw a block diagram using the diagramming tool to augment your design. If you are unfamiliar with the tool, you can simply describe your design to the chat bot and ask it to generate a starter diagram for you to modify...







Request flows

Explain how the request flows from end to end in your high level design. Also you could draw a sequence diagram using the diagramming tool to enhance your explanation...






Detailed component design

Dig deeper into 2-3 components and explain in detail how they work. For example, how well does each component scale? Any relevant algorithm or data structure you like to use for a component? Also you could draw a diagram using the diagramming tool to enhance your design...






Trade offs/Tech choices

Explain any trade offs you have made and why you made certain tech choices...






Failure scenarios/bottlenecks

Try to discuss as many failure scenarios/bottlenecks as possible.






Future improvements

What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?