電腦科學基礎：程式/進程/執行緒、記憶體管理與 GC、作業系統核心概念（排程、死鎖、IPC、虛擬記憶體）、網路協定、資料結構與演算法複雜度速查。
FAQ - Frequently Asked Questions
Interview preparation FAQs covering Java, Backend, Database, Streaming, and more.
General11 docs
Covers: 0. Data Engineer Interview Questions With Python · 1. Difference between file format and storage system ? · 2. Difference between Cluster and Node?
Covers: 1) What are the different design schemas in Data Modelling? Explain with the example? · 2) Which schema is better – star or snowflake? · 3) What is a fact, dimension table ?
Covers: What a behavioral round assesses · Why it matters · How it’s scored
Covers: 1. Docker 基礎 · 容器 vs 虛擬機 · Dockerfile 重要概念
Practical, language-neutral notes on how to find and fix performance problems, with Java-specific tips at the end.
the Python language itself: object model, mutability, functions and decorators, iterators, OOP, memory management, typing, packaging and the gotchas interviewers actually probe.
how Python actually runs concurrent work: the GIL, threads vs processes vs asyncio, the synchronisation primitives, and how to pick between them.
How a program is loaded, laid out in memory, and executed — the concepts that come up in systems and language-internals interviews.
Java14 docs
splitting a system's write model from its read model: what CQRS buys (simplicity, scalability, speed), what it costs (eventual consistency, projectors, duplication), and when it is worth it.
OOP fundamentals for Java interviews: the four pillars, interface vs abstract class, composition over inheritance, SOLID and the everyday principles, and the object contracts.
core language mechanics: primitives vs references, strings, initialisation order, Object's methods, nested classes, reflection, I/O and the date/time API.
the collections framework: the hierarchy, ArrayList vs LinkedList, HashMap and ConcurrentHashMap internals, and the Big-O of every operation.
the GoF patterns that actually come up in Java interviews and code review, each with a minimal snippet and the place the JDK or Spring already uses it.
the Throwable hierarchy, checked vs unchecked, try/catch/finally mechanics, try-with-resources, and the design rules for exceptions in application code.
the Java 8 functional toolkit: lambdas, method references, the built-in functional interfaces, the Stream API, collectors, and Optional.
type parameters, type erasure and everything that follows from it: bounded types, wildcards and PECS, generic methods, and why generic arrays are illegal.
what changed after Java 8: var, records, sealed types, pattern matching, text blocks, the module system, and virtual threads.
writing correct concurrent Java: thread lifecycle, synchronized and ReentrantLock, CAS and atomics, thread pools, CompletableFuture, ThreadLocal and the concurrent collections.
the container (IoC/DI, bean lifecycle and scopes), AOP, @Transactional semantics, Spring MVC's request path, Spring Boot auto-configuration, and testing.
test-driven development in Java: the red-green-refactor cycle, JUnit 5, the AAA structure, mocking, and what is worth testing.
the rules for when one thread's write becomes visible to another: atomicity, visibility, ordering, happens-before, and what volatile, synchronized and final each guarantee.
how the JVM stores, executes and reclaims: runtime memory areas, object creation, garbage collection and collectors, reference strengths, class loading, JIT, and the flags/tools used to diagnose a sick JVM.
Backend10 docs
designing an HTTP API: resource modelling, status codes, idempotency, pagination, versioning, error shape, auth, and how REST compares with GraphQL and gRPC.
Covers: 1. Session（傳統方式） · 運作流程 · Session 儲存位置
Covers: High Traffic Patterns · 1. Idempotent Request Processing · Initial Design (V0 - Interview Whiteboard)
Covers: Thread Pool & Executor Framework · 1. ThreadPoolExecutor Deep Dive · 2. Rejection Policies Comparison
Covers: Advanced Concurrency · 1. Fork/Join Framework · 2. Lock-Free Programming
Covers: 設定隔離級別 · Session 級別（當前連線） · 全域級別（影響所有新連線）
Covers: 1. 什麼是冪等性 · 2. 為什麼 LLM 工具特別需要冪等性 · 3. 基礎實作：Check-Act-Record
Covers: Problem · Strategies · 1. Atomic DECR (Redis)
Covers: 1. HTTP Keep-Alive (Persistent Connection) · 2. HTTP Pipelining · 3. Long Polling
Covers: 1. 資料庫相關 · 1.1 資料庫隔離級別 (Transaction Isolation Levels) · ACID 特性
Database3 docs
Covers: 1) DB type · 2) DB properties · 3) DB design
Covers: 1) array_to_string : array to str · 2) cast : type transform · 2’) to_char : type transform
SQL2 docs
Covers: Dirty read, Lost of modify, Unrepeatable read, Phantom read · MySQL index · MySQL explain (execution plan)
Covers: 1. Given 2 table a (3k rows), b (4k rows), what’s the · 2. Difference between full outer Join And Union in SQL ? · 3. Find the orders in Quater ? (no hard-code)
Redis3 docs
Covers: Redis data structure · Redis部署模式 · Why redis is fast?
Redis is a powerful, open-source in-memory data structure store that is widely used in modern backend systems. It is often utilized for caching, session storage, real-time analytics, and messaging systems, among other use cases.
Covers: Sorted set (ZSET) · 🧠 Redis Sorted Set Primer · ✅ Basic Leaderboard Operations with Redis
Kafka1 doc
Covers: 1) Explain kafka architecture ? · 1’) Kafka message structure ? · 1’') How kafka find .log file via index ?
Spark & Hadoop3 docs
Flink1 doc
Covers: 1. What is Apache Flink? · 2. Explain Apache Flink Architecture? · 2’ Explain Apache Flink execution graph and its step ?
Streaming1 doc
Covers: Simple stream from scratch · Merge multiple input stream into one
💡 Tip: These FAQs are designed for quick reference during technical interview preparation.
View all FAQs on GitHub.