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2 billion DAU
100 to 1 read to write ratio
post 1KB
ratio of images 0.6 and average size of 1MB
ratio of videos 0.1 and average size of 10MB
Posts uploaded a day: 10^9
Posts read a day: 100* 10^9
Storage capacity:
Posts: 10^9*1KB = 1TB a day -> 365TB a year -> 1.8PB 5 years
Images: 0.6*10^9*1MB = 0.6PB a day -> 219PB a year -> 1EB 5 years
Images: 0.1*10^9*10MB = 1PB a day -> 365PB a year -> 1.8EB 5 years
Total Storage: 585PB a year
Bandwidth
2PB a day -> 2PB/(24*60*60) * 8 = 184Gbps
Server for peak load:
assuming dau can be peak load and each server can handle 64000 requests
2*10^9/64000 = 31250
POST /api/v1/post
{
auth_token,
content,
image_ref,
video_ref,
}
Get /api/v1/posts/{post_id}
{
content,
image_ref,
video_ref,
}
Get /api/v1/newsfeed?limit={x}&since={last_check_time}
({user_id} is fetched from auth_token)
[post_ids]
POST /api/v1/posts/{post_id}/like
POST /api/v1/posts/{post_id}/unlike
POST /api/v1/posts/{post_id}/comment
{
comment_content
}
GET /api/v1/posts/{post_id}/comments
[comments_id]
GET /api/v1/comments/{comment_id}
{
sender_id,
comment_content
}
POST /api/v1/follow
{
followee_id
}
(follower_id is fetched from auth_token)
Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your 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...
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...
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...
Explain any trade offs you have made and why you made certain tech choices...
Try to discuss as many failure scenarios/bottlenecks as possible.
What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?