# Vivek Kushwaha | R2
- Solved the System design for click events
- Solved the basics of chat system
- Both the solutions have scaling issue.
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# Question 1: HLD : capture click events : clevertap

Website/App - > users active

capture click events.

id:
session_id:
enevt type: button click/ coupons /
time_spent:
created:

client -> load balancer -> event tracking service -> DataBase

# Question 2: Chat System

1<>1 chat
text messages.

- list of conversations
- list of messages

Chat:
id: uuid
created_at: timestamp

user_caht:
user_id: uuid
chat_id: uudi

message:
id: uuid
chat_id: uuid
message: text
sent_by: uuid
created_at: timestamp

list of
:

select chat_id, max(created_at) as latest_message from user_chat join message on message.chat_id=user_chat.id where user_chat.user_id = <my_user_id> group by chat_id order by latest_message desc;