Database indexing in HLD - Architecture Diagram

System Overview - Database indexing

This system explains how database indexing improves data retrieval speed. It shows how queries use indexes to find data faster instead of scanning the whole database. The key requirement is to reduce query response time while keeping data consistent.

Architecture Diagram

User
  |
  v
Load Balancer
  |
  v
API Server
  |
  v
Database Engine
  |       
  |---> Index Structure (B-Tree)
  |
  v
Data Storage

Components

User

client

Sends data queries to the system

Load Balancer

load_balancer

Distributes incoming requests evenly to API servers

API Server

service

Receives queries and interacts with the database engine

Database Engine

service

Processes queries using indexes and accesses data storage

Index Structure (B-Tree)

index

Organizes keys to quickly locate data without scanning entire storage

Data Storage

database_storage

Stores the actual data records on disk

Request Flow - 10 Hops

User → Load Balancer

Load Balancer → API Server

API Server → Database Engine

Database Engine → Index Structure (B-Tree)

Index Structure (B-Tree) → Database Engine

Database Engine → Data Storage

Data Storage → Database Engine

Database Engine → API Server

API Server → Load Balancer

Load Balancer → User

Failure Scenario

Component Fails:Index Structure (B-Tree)

Impact:Queries slow down significantly because the database must scan all data records without index help.

Mitigation:System falls back to full table scan; rebuild or repair index asynchronously to restore performance.

Architecture Quiz - 3 Questions

Which component helps the database find data quickly without scanning all records?

A Load Balancer

B API Server

C Index Structure (B-Tree)

D Data Storage

Design Principle

Using an index structure like a B-Tree allows the database engine to quickly locate data without scanning the entire dataset. This improves query performance significantly. The architecture separates concerns by using a load balancer to distribute requests and an API server to handle queries before reaching the database engine.