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HLDsystem_design~12 mins

Pagination patterns (cursor, offset) in HLD - Architecture Diagram

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System Overview - Pagination patterns (cursor, offset)

This system demonstrates two common pagination methods used in APIs and databases: offset-based and cursor-based pagination. It supports efficient data retrieval for large lists by dividing results into pages, improving user experience and reducing server load.

Architecture Diagram
User
  |
  v
Load Balancer
  |
  v
API Gateway
  |
  +--------------------+
  |                    |
  v                    v
Offset Pagination Service  Cursor Pagination Service
  |                    |
  v                    v
Database <------------ Cache
Components
User
client
Initiates requests for paginated data
Load Balancer
load_balancer
Distributes incoming requests evenly to API Gateway instances
API Gateway
api_gateway
Routes requests to the appropriate pagination service
Offset Pagination Service
service
Handles pagination using offset and limit parameters
Cursor Pagination Service
service
Handles pagination using cursor tokens for efficient navigation
Database
database
Stores the full dataset and responds to queries
Cache
cache
Stores frequently accessed pages or cursor results to reduce database load
Request Flow - 18 Hops
User → Load Balancer
Load Balancer → API Gateway
API Gateway → Offset Pagination Service
API Gateway → Cursor Pagination Service
Offset Pagination Service → Cache
Cursor Pagination Service → Cache
Cache → Offset Pagination Service
Cache → Cursor Pagination Service
Offset Pagination Service → Database
Cursor Pagination Service → Database
Database → Offset Pagination Service
Database → Cursor Pagination Service
Offset Pagination Service → Cache
Cursor Pagination Service → Cache
Offset Pagination Service → API Gateway
Cursor Pagination Service → API Gateway
API Gateway → Load Balancer
Load Balancer → User
Failure Scenario
Component Fails:Cache
Impact:Cache misses increase, causing more direct database queries and higher latency
Mitigation:System continues to function by querying the database directly; cache rebuilds on new queries
Architecture Quiz - 3 Questions
Test your understanding
Which component routes the user request to the correct pagination method?
AAPI Gateway
BLoad Balancer
CCache
DDatabase
Design Principle
This architecture shows how separating pagination logic into offset and cursor services allows flexibility and scalability. Using a cache reduces database load and improves response times. Routing through API Gateway and Load Balancer ensures organized traffic flow and fault tolerance.