Search

Lessons (40)

• Cost Optimization and the Well-Architected Framework

  … Savings Plans save money but reduce agility. Worked cost review: cost per accepted order A monthly bill alone …

• YAGNI: You Aren't Gonna Need It

  … You pay for it four times: mermaid flowchart TD F[Feature built 'just in case'] -- C1["1️⃣ Cost …

• KISS: Keep It Simple, Stupid

  … 10 }; const DEFAULT SHIPPING COST = 20; const getShippingCost = (country) = SHIPPING COST[country] ?? DEFAULT SHIPPING COST; KISS in architecture …

• Putting AI Systems into Production

  Design dependable model integrations with fallbacks, observability, versioning, cost controls, and human review. The big idea A production …

• Monolith vs Microservices

  What microservices really are, what they cost, and when they're worth it. Compare monoliths, modular monoliths and …

• AWS: Start Here

  … If the session expires, sign in again rather than creating permanent access keys as a shortcut. Plan cost …

• VPC Endpoints, Transit Gateway and Hybrid Networking

  Keep traffic private, cut NAT costs, connect many VPCs, link to on-premises networks, and troubleshoot with flow …

• What Is Software Architecture?

  … attribute usually costs another: You gain… You often pay with… --- --- Scalability (microservices) Simplicity, consistency, operating cost Performance (caching …

• Views, Triggers & Stored Procedures

  … be stale. Type Read behavior Cost --- --- --- View Runs the base query Query cost each read Materialized view Reads …

• AWS Interview Questions: Clear Answers

  … AWS operates the server fleet, but you manage code, permissions, timeouts, concurrency, monitoring, and cost. Event retry behavior …

• Architecture Patterns at Scale

  … Extract a service only when independent scaling, releases or ownership justify its network and operational costs. 3. Use …

• Batch vs Stream and Data Modeling

  … read and write cost](/img/system-design-l6/batch-stream.svg) Choice Use when Cost --- --- --- Batch Reports, backfills …

• Design a Logging and Monitoring Platform

  … Measure ingestion lag, dropped samples, query latency, cardinality and storage cost. Design the data lifecycle Collect structured events …

• Serverless Architecture

  … invest in structured logs, tracing (X-Ray / OpenTelemetry) Cost at sustained high load Containers or VMs can be …

• What to Learn in AI, and in What Order

  … 6. Reliable delivery: Evaluate quality, protect data, address abuse and prompt injection, manage latency and cost, and monitor …

• Database Indexing & Transactions

  … reads every row Seq Scan on users (cost=0.00..18334.00 rows=1) (actual time=0.03 …

• Containers at Scale: ECS Deep Dive and EKS

  … tasks cannot be placed. Fargate Spot can cut cost for interruptible workers, as it can reclaim capacity with …

• AI Evaluation, Safety, and Security

  … Measure latency and cost alongside quality. Test changes to the model, prompt, index, and preprocessing against a stable …

• Transformers and Large Language Models

  … Long context can help, but it increases cost and does not guarantee the model will reliably use every …

• Big Data: ETL, Warehouses and Streaming

  … Partition by query patterns and constrain scan cost; avoid two independent business-rule implementations where possible. Walk through …

• Arrays & Strings

  … the computer calculates start address + i × box size and jumps there directly. The cost of each operation Operation …

• Machine Learning Fundamentals

  … we catch?” The right tradeoff depends on the cost of missed fraud versus investigating a false alert. Generalization …

• Caching, Consistent Hashing and Sharding

  Move reads close to users, distribute data safely, and understand cache and database consistency costs. The problem in …

• Scalable Frontend Architecture

  … introduce shared-runtime, routing, visual-consistency and observability costs. They are not a cure for a poorly separated …

• Code Profiling

  … a faster request, smoother interaction, lower cost, or fewer crashes. Start with a realistic workload and a clear …

• SQL Language, Identifiers & Data Types

  … UUIDs can be generated without a central counter and help distributed writes, but cost more index space. Generated …

• Stacks & Queues

  … First to arrive, first to be served. Stack Operation Meaning JS Cost --- --- --- --- push(x) put on top arr …

• Capacity Planning, SLOs and Error Budgets

  Turn vague scale requirements into traffic, latency, availability and cost decisions that a team can operate. The problem …

• Storage Engines & Database Operations

  … recoverability](/img/database/storage-operations.svg) Mechanism Strength Cost to remember --- --- --- B-tree Point/range reads and ordered …

• Indexes, EXPLAIN & Query Plans

  … The cost is extra disk, memory, write work and maintenance. ![An index lets the database seek to matching …

• Resilience, Disaster Recovery and Multi-Region Design

  … Tighter targets cost much more, so define them per workload , not for everything. Failure scopes Scope Example failure …

• AI Agents and Tool Use

  … bound the loop. - Add human approval for sensitive, costly, or irreversible actions. - Prefer deterministic workflows when the process …

• Choosing an Architecture

  … processing, zero-ops Cold starts, limits, lock-in, cost at scale A decision guide mermaid flowchart TD Start …

• Embeddings, Semantic Search, and RAG

  … Overlap can preserve boundaries, but excessive overlap duplicates content and increases cost. Trust and access control Retrieved text …

• CloudFront: Faster Websites and Safer File Delivery

  … Avoid frequently invalidating every path; invalidations cost time and can cost money. Protection AWS WAF can block common …

• CloudWatch: Know What Your App Is Doing

  … Logs Insights queries can incur scan costs, so avoid querying every log group over an unnecessarily broad time …

• AWS Data Pipelines in Plain Language

  … it is compressed and column-oriented, so Athena scans less data and costs less. Partition files by a …

• Caching & Redis

  … The first request after expiry pays the database cost, so protect hot keys with a lock or request …

• React Internals & Concurrent Rendering

  … filter], ); useMemo helps only when the calculation is costly or its stable identity prevents a measured downstream render …

• System Design Interview Framework

  … 7. Close with failure modes, observability, cost and evolution. State assumptions aloud. Keep the first design simple, name …