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Lessons (19)

• DBMS Foundations, Keys & Normalization

  Detailed interview answers for DBMS advantages, normalization, keys, abstraction and conceptual design. Covers PDF questions 1-5, 12 …

• Normalization & Denormalization

  … one fact, one home Normalization organizes a relational database so a fact is stored once, in the table …

• Design a Polite Web Crawler

  … Workers fetch, checksum, parse, normalize links and enqueue unseen candidates. A Bloom filter cheaply says definitely unseen or …

• Batch vs Stream and Data Modeling

  … Stream Fraud alerts, live dashboards Ordering/replay/deduplication Normalized tables Integrity and flexible writes Reads may join Denormalized …

• Capacity, Availability, Latency and CAP

  … Payments/inventory normally reject uncertain writes; feeds/counters can serve a stale value. CAP is about partitions, not …

• Debug Latency Like an Investigator

  … the shape, not a guess If p50 is normal but p99 grows, a smaller group is queued, locked …

• The L6 System-Design Thinking Loop

  … Draw the smallest normal-load design. 3. Name the first peak bottleneck. 4. Walk one crash, timeout, or …

• How Browsers Render a Page

  … can block everything When the parser meets a normal <script , it stops building the DOM , downloads and runs …

• ACID, Transactions & Locks

  … A deadlock happens when transactions wait in a cycle; databases normally abort one. Retry only the aborted transaction …

• CQRS & Event Sourcing

  … commands W["✍️ Write model<br/ business rules,<br/ normalised DB"] W -- events P["🔄 Projector"] P -- R[("📖 Read model …

• Choosing an Architecture

  … heavy ML scaling)"] Each part uses the style that fits its needs , and that's normal. Consistency within …

• Clean Error Handling

  … false, error: "Not a number" }; } Common mistakes - Using exceptions for normal control flow (for example, throwing to exit …

• REST vs GraphQL vs gRPC

  … Mixing them is normal.

• JavaScript Essentials: Event Loop, Closures & this

  … do list Promise callbacks, queueMicrotask Task (macrotask) queue 📋 Normal to-do list setTimeout , clicks, network events Event loop …

• Layered (N-Tier) Architecture

  … string) { return this.repo.findById(id); // just a pass-through } } A few pass-throughs are normal. If most …

• DSA Interview Patterns Cheat Sheet

  … 2. Examples: work one normal example and one edge case by hand. 3. Brute force: say it out …

• Observability: Logs, Metrics & Traces

  … production? --- --- --- debug Detailed developer info Usually off info Normal business events (order placed) ✅ warn Something odd but handled …

• Resilience Patterns

  … trial call fails ❌ note right of Closed Normal: calls go through end note note right of Open Calls …

• Frontend Performance & Core Web Vitals

  … a store with selectors mermaid flowchart LR subgraph Normal["10,000 DOM rows 🐢"] n1[row 1] --- n2[row …