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Lessons (27)

• SQL Language, Identifiers & Data Types

  Interview answers for DDL/DML/DCL, generated IDs, UNION, static/dynamic SQL and CHAR/VARCHAR. Covers PDF questions …

• Design a URL Shortener

  … durable mappings, cache-backed redirects and asynchronous analytics](/img/system-design-l6/url-shortener.svg) Generate a Base62 …

• TypeScript Essentials

  … That's a whole class of UI bugs gone. Generics: types with parameters A generic is a type …

• SOLID at a Glance

  … js // ❌ Breaks almost every SOLID rule class Report { generate(data) { / build numbers / } toPdf() { / PDF logic / } toExcel() { / Excel logic …

• Domain-Driven Design: Strategic Design

  … invest in the core , keep supporting simple, buy generic . - Speak a ubiquitous language , in conversation and in code …

• Finding Service Boundaries with DDD

  … returns handling"] -- SupHow["Build simply,<br/ or outsource"] Generic["📦 Generic<br/ everyone needs it<br/ e.g. auth …

• Next.js Rendering: CSR, SSR, SSG, ISR & Server Components

  … Static Site Generation Pages are rendered once at build time into HTML files and served from a CDN …

• Replication, Partitioning & Sharding

  … Plan the router, shard map, ID generation, backups, rebalancing and degraded behavior before splitting. Cross-shard joins and …

• Binary Search

  … 0 1 2 3 4 5 6 condition: ❌ ❌ ❌ ✅ ✅ ✅ ✅ ↑ find the first ✅ js // Generic: smallest x in [lo, hi …

• REST vs GraphQL vs gRPC

  … tools generate client and server code in Go, Java, Node.js, Python… js // Node.js client (generated stubs …

• Behavioral Patterns II: Chain, Template, Iterator, Mediator, Memento, Visitor

  … constructor(songs) { this.songs = songs; } [Symbol.iterator]() { // a generator makes iterators easy for (const song of this.songs …

• What Are Design Patterns?

  … cached). - Iterator → built in with Symbol.iterator and generators. This course shows the idiomatic JavaScript version of each …

• I — Interface Segregation Principle

  … OrderReader & OrderWriter) {} } Key takeaways - Many small, focused interfaces beat one large, general one. - If implementers throw "not supported …

• YAGNI: You Aren't Gonna Need It

  … feature with 3 users Clear names and structure Generic BaseAbstractManager<T classes Error handling and security Caching layer …

• DRY: Don't Repeat Yourself

  … API types written by hand in the client Generate types from OpenAPI / GraphQL schema Config values copied between …

• Meaningful Names

  … SHIPPED = 5; if (status === ORDER STATUS SHIPPED) {} const generatedAt = new Date(); Rule 6: Length should match scope mermaid …

• Clean Error Handling

  … Use specific error types Generic Error("something failed") forces callers to parse strings. Custom error classes let them …

• Deployments, ReplicaSets & Rollouts

  … registry.example.com/reports:2.1.0 args: ["generate", "--date=yesterday"] 💡 Running databases on Kubernetes (StatefulSets) is possible …

• Backend Languages: Node.js, Go, Python & Rust

  … raise HTTPException(status code=404, detail="Not found") return user FastAPI generates OpenAPI docs automatically from type hints …

• Recursion & Backtracking

  … Queens, Sudoku solver, word search in a grid, generating valid parentheses. Key takeaways - Recursion = base case + smaller recursive …

• Graphs: BFS & DFS

  … a special case of graphs (connected, no cycles). General graphs can have cycles , many paths and disconnected parts …

• Kafka Producers

  … schema registry Protobuf Compact, typed, great tooling Needs generated code A Schema Registry (Confluent, Apicurio) stores versioned schemas …

• API Gateway, BFF & Service Discovery

  … One generic API serves nobody well. A BFF is a small backend tailored to one frontend , owned by …

• What Is Software Architecture?

  … inside one container Developers 4. Code Classes (usually generated or skipped) Rarely needed mermaid flowchart LR U["👤 Customer …

• REST API Design

  … From it you get interactive docs, client SDK generation, request validation and contract tests. yaml paths: /users/{id …

• Helm, kubectl Cheat Sheet & Best Practices

  … Dry run + diff kubectl diff -f app.yaml Generate YAML kubectl create deploy web --image=nginx --dry-run …

• Domain-Driven Design: Tactical Patterns

  … Use value objects generously. - Aggregates are consistency boundaries: small, changed through the root, referenced by ID, one per …