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Lessons (26)

• Atomic Design & Component Libraries

  … Start with small, reusable building blocks and combine them into increasingly complete screens: mermaid flowchart BT A[Atoms …

• Design a Ride-Sharing Service

  … a geo index finds candidates, an atomic assignment leases a driver, and live updates flow separately](/img/system …

• Flash Sale: 10 Million Buyers, No Oversell

  … The durable inventory owner decides the winner atomically. The problem in context A store has 1,000 discounted …

• ACID, Transactions & Locks

  Make multi-step changes correct with atomic transactions, isolation choices, constraints and short-lived locks. The bank-transfer …

• Go Concurrency: Goroutines, Channels and Context

  Concurrency vs parallelism, goroutines and the scheduler, buffered and unbuffered channels, select, WaitGroup, Mutex and atomics, worker pools …

• Payment Retries: Prevent Duplicate Charges

  Safe payment retries need a durable idempotency record, atomic state transition and provider-side deduplication. The problem in …

• Normalization & Denormalization

  … First I make values atomic in 1NF. If I have a composite key, I move fields that depend …

• Time, Consistency and Distributed Transactions

  … Avoid distributed locks where atomic database/queue claiming owns the state. Two-phase commit offers coordinated atomicity but …

• Delivery Guarantees: At-Most, At-Least & Exactly Once

  … Transactions (atomic read-process-write) A stream processor reads from topic A, transforms the record, and writes to …

• Design an E-Commerce Checkout

  … reserve inventory atomically, create/get a payment attempt with an idempotency key, then commit an order and publish …

• A WhatsApp OTP Is Only Single Use If You Make It So

  … hashed codes, atomic consume, attempt limits, crash recovery and race-condition tests. The problem in context A user …

• Transactions, Indexes & Concurrency

  … so they commit together or roll back together. Atomicity is all-or-nothing; consistency preserves constraints; isolation defines …

• Database Indexing & Transactions

  … let the database do it atomically sql UPDATE flights SET seats left = seats left - 1 WHERE id = 42 …

• Concurrency, Resilience & Distributed Workflows

  … Prefer an atomic database statement or a transaction that owns the invariant: sql UPDATE inventory SET available = available …

• Design System Operations

  … process. A component library needs a contract The Atomic Design lesson explains composition. Operating a design system means …

• Big Data: ETL, Warehouses and Streaming

  … Publish the replacement atomically instead of exposing a half-rebuilt report. How to prove it worked Reconcile reported …

• Distributed Coordination: Consensus, Heartbeats and Gossip

  … Raft/consensus cluster. Protect a payment/inventory write Atomic transaction at the durable owner. Consensus is powerful but …

• Storage, Search and Location Queries

  … The final assignment still needs a durable, atomic claim so two riders cannot both receive the same driver …

• Message Delivery: Queues, Kafka, Ordering and DLQs

  … Commit a local effect plus processing marker atomically where possible. 3. Bound retries and quarantine poison events with …

• The L6 System-Design Thinking Loop

  … can wait and which database write must remain atomic? --- Concepts and implementation details The big idea An L6 …

• DynamoDB Modeling, RDS Scaling and Data Resilience

  … In a dedicated sample table with that key schema, an atomic conditional update can decrement only when stock …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … A single boolean does not make an external side effect atomic. Use a stable operation key, a conditional …

• Domain-Driven Design: Tactical Patterns

  … Promise<void ; // saves the WHOLE aggregate atomically nextId(): OrderId; } ⚠️ No repository for OrderLine . Lines are only reachable through …

• Rust: Types, Errors and Concurrency

  … Graph/tree nodes with several parents Arc<T Atomic Rc , safe across threads Shared config or state in …

• 500 Users Upload Documents at Once: Design the Background Job Pipeline

  … This is the same atomic-check-and-set idea used for idempotent payments and single-use OTPs. The …

• Backend Design Scenarios

  … separate quota and emergency fallback Make the decision atomic ( INCR plus expiry or a Lua script), set short …