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HLDsystem_design~12 mins

Connection pooling in HLD - Architecture Diagram

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System Overview - Connection pooling

Connection pooling is a technique used to manage database connections efficiently. It keeps a set of open connections ready to be reused, reducing the overhead of opening and closing connections for each request. This improves performance and resource usage in systems that frequently access databases.

Architecture Diagram
User
  |
  v
Load Balancer
  |
  v
API Server
  |
  v
Connection Pool Manager
  |
  +-------------------+
  |                   |
  v                   v
Database Connection 1  Database Connection 2
  |                   |
  +-------------------+
Components
User
client
Initiates requests to the system
Load Balancer
load_balancer
Distributes incoming requests evenly across API servers
API Server
service
Handles user requests and interacts with the connection pool
Connection Pool Manager
connection_pool
Manages a pool of reusable database connections to reduce connection overhead
Database Connection 1
database_connection
An open connection to the database ready for use
Database Connection 2
database_connection
Another open connection to the database ready for use
Request Flow - 9 Hops
User → Load Balancer
Load Balancer → API Server
API Server → Connection Pool Manager
Connection Pool Manager → Database Connection 1
API Server → Database Connection 1
Database Connection 1 → API Server
API Server → Connection Pool Manager
API Server → Load Balancer
Load Balancer → User
Failure Scenario
Component Fails:Connection Pool Manager
Impact:API servers cannot get database connections, causing request failures or delays
Mitigation:Implement health checks and fallback to direct connection creation temporarily; scale pool manager horizontally for high availability
Architecture Quiz - 3 Questions
Test your understanding
What is the main purpose of the Connection Pool Manager?
ATo balance user requests across API servers
BTo store user session data
CTo keep database connections open and reuse them to reduce overhead
DTo cache database query results
Design Principle
Connection pooling improves system performance by reusing open database connections, reducing the time and resources needed to establish new connections for each request. It also helps manage limited database connections efficiently.