System Design Interview: Multi-Region Active-Active Architecture
Why Multi-Region Active-Active? A single-region active-passive setup (one primary region serves traffic, one standby region for failover) has two problems: […]
System Design
System Design
System Design Interview: Two-Phase Commit and Distributed Transactions
The Distributed Transaction Problem A transaction that spans multiple databases or services must either fully commit on all participants or
System Design
System Design Interview: Kubernetes Autoscaling (HPA, VPA, KEDA, and Cluster Autoscaler)
Why Autoscaling? Manual capacity planning is expensive and error-prone. Too much capacity wastes money; too little causes outages under traffic
Algorithms
PHP Interview Questions (2025): OOP, Performance, and Modern PHP
PHP Interview Questions Overview PHP powers 77% of websites with a server-side language (including WordPress, Facebook’s HHVM era, Shopify’s partner
System Design
System Design Interview: Service Mesh and Microservice Communication
What Is a Service Mesh? A service mesh is a dedicated infrastructure layer for managing service-to-service communication in a microservices
System Design
System Design Interview: Data Warehouse and OLAP Architecture
What Is a Data Warehouse? A data warehouse (DW) is an analytical database optimized for reading large volumes of historical
Algorithms
String and Array Manipulation Interview Patterns
String and Array Patterns Overview String and array manipulation problems are a staple of coding interviews at every level. The
System Design
System Design Interview: Zero-Downtime Deployments
Why Zero-Downtime Deployments Planned downtime windows are increasingly unacceptable — global users span every time zone, and even brief outages
System Design
System Design Interview: Raft Consensus Algorithm Deep Dive
Why Consensus Matters Distributed systems need to agree on values — which server is the primary, what the current config
Algorithms
Ruby on Rails Interview Questions (2025)
Rails Interview Questions Overview Ruby on Rails powers Shopify, GitHub (partially), Airbnb, and many startups. Senior Rails interviews test deep
System Design
System Design Interview: GraphQL API at Scale
Why GraphQL for Large APIs GraphQL solves two fundamental REST API problems: over-fetching (the response includes fields the client doesn’t
Algorithms
Interval and Greedy Interview Patterns: Meeting Rooms, Job Scheduling, and Activity Selection
Why Greedy and Interval Problems Greedy algorithms appear frequently in FAANG interviews because they test whether you can identify when
System Design
System Design Interview: Serverless Architecture and Function-as-a-Service
What Is Serverless? Serverless (Function-as-a-Service / FaaS) lets you deploy individual functions without managing servers. AWS Lambda, Google Cloud Functions,
System Design
System Design Interview: Event Sourcing and CQRS
What Is Event Sourcing? Traditional systems store the current state of data (the latest balance in a bank account, the
Algorithms
Segment Tree and Fenwick Tree: Range Query Interview Patterns
When to Use Range Query Data Structures Range query problems appear frequently in senior engineering interviews and competitive programming: “find