标签：#interview

If you're prepping for a Business Intelligence (BI) Engineer, Data Analyst, Data Engineer, or Data Scientist role at Amazon, you probably already know SQL matters. It's a core part of the hiring bar. But Amazon isn't just checking your syntax. They want to see if you can think in sets, write clean queries under pressure, and reason about data the way the business actually uses it. Here's exactly how to prepare based on what the interview actually rewards. What the Interview Really Tests Amazon's SQL rounds usually show up in one of two ways. It's either a technical screen using a shared coding tool, or a whiteboarding case-study during the main loop. Either way, the interviewer is watching for a few specific signals. For starters, correctness always beats speed. A working query is far better than a clever one that fails. Communication is also huge. Do you talk through your logic before you even touch the keyboard? You'll often get a vague ask, like finding the "best" customers. You are completely expected to define what "best" means out loud before you start writing Common Table Expressions (CTEs). And watch out for messy data. Nulls, duplicates, and mismatched grain are almost always baked into the problem on purpose. The Core Topics to Master Focus your prep time on a few specific areas. Actually, it turns out this is where almost all the interview questions live. Joins Inside and Out You need to know your INNER, LEFT, RIGHT, and FULL OUTER joins cold. Be ready to explain exactly why row counts change after each one. A classic Amazon-style question is finding customers who placed orders but never left a review. That's just a LEFT JOIN with a NULL check. The interviewers want to see you reach for it right away. Window Functions Functions like ROW_NUMBER() , RANK() , DENSE_RANK() , and LAG() or LEAD() show up constantly. You might see a common pattern—like finding the second-highest order value per customer, or calculating month-over-month growth. If you're shaky he

Andy Holloway cohosts the Fantasy Footballers podcast with his friends Jason Moore and Mike Wright. The show is one of the premier fantasy sports podcasts, netting over 2 million monthly listeners and numerous awards, including Best Sports Podcast from iHeartRadio and People's Choice at the Podcast Awards four years in a row. Holloway's goal has […]

Full interview-prep notes, ##Episode 1 through 29. Episode 1 : Execution Context ============================== Everything in JS happens inside the execution context. Imagine a sealed-off container inside which JS runs. It is an abstract concept that hold info about the env. within the current code is being executed. In the container the first component is memory component and the 2nd one is code component Memory component has all the variables and functions in key value pairs. It is also called Variable environment. Code component is the place where code is executed one line at a time. It is also called the Thread of Execution. JS is a synchronous, single-threaded language Synchronous:- In a specific synchronous order. Single-threaded:- One command at a time. Episode 2 : How JS is executed & Call Stack ============================================= When a JS program is ran, a global execution context is created. The execution context is created in two phases. Memory creation phase - JS will allocate memory to variables and functions. Code execution phase Let's consider the below example and its code execution steps: var n = 2 ; function square ( num ) { var ans = num * num ; return ans ; } var square2 = square ( n ); var square4 = square ( 4 ); The very first thing which JS does is memory creation phase, so it goes to line one of above code snippet, and allocates a memory space for variable 'n' and then goes to line two, and allocates a memory space for function 'square'. When allocating memory for n it stores 'undefined', a special value for 'n'. For 'square', it stores the whole code of the function inside its memory space. Then, as square2 and square4 are variables as well, it allocates memory and stores 'undefined' for them, and this is the end of first phase i.e. memory creation phase. Now, in 2nd phase i.e. code execution phase, it starts going through the whole code line by line. As it encounters var n = 2 , it assigns 2 to 'n'. Until now, the value of 'n' wa

Most EM interview prep fails the same way. You pick three strong stories, polish them until they're tight, run them past a friend, and walk in confident. Then somebody asks how you'd handle a high performer who's difficult to work with, and none of your three stories touch it. That isn't a depth problem. It's a coverage problem, and it's the thing that makes the EM loop different from every IC loop you've done. An IC loop samples from a narrow surface. Systems, code, a couple of behavioural questions that mostly serve as tiebreakers. You can prepare for it by going deep on a small number of technical narratives. An EM loop samples from a wide one. Nine areas, roughly, and you can be excellent at seven of them and still lose the loop on the two you never thought about. The nine areas Team building and hiring Performance management and difficult conversations Conflict and difficult relationships Delivery, prioritization and ambiguity Cross-functional partnership Growth, coaching and career development Technical judgment and architecture Values, culture and self-awareness Vision and scaling Look at that list and be honest about which two are thin for you. For most people coming from a senior IC role it's 2 and 3, because those are the parts of the job you've watched from the outside rather than done. What the questions are actually checking Underneath the surface wording, almost every behavioural question in an EM loop is checking one of four things. Did you run a real process, or improvise? "I had a conversation with them" is an improvisation. "I named the specific pattern with dates, we agreed a 30-day plan, I checked in weekly" is a process. Can you name a specific tradeoff you made, and why? Not that tradeoffs existed. Which one you picked, what it cost, and what you got. Do you own outcomes without deflecting or over-apologizing? Both failure modes read badly. Blaming the org is worse, but flagellating yourself for four minutes over a bad hire is not much better.

Joseph Fink is the cocreator and cowriter of Welcome to Night Vale, arguably the most important fiction podcast ever. He's also the creator of the noir podcast Unlicensed and Alice Isn't Dead, which takes some of the conspiratorial cosmic horror of Night Vale and turns it into fodder for a more serious series about relationships, […]

July wasn’t a particularly pleasant month for me. I was affected by the restructuring of the company...

The strongest candidate I ever voted no on solved the problem in eleven minutes. Clean. Optimal. Caught the edge case I normally have to hint at twice. Then I opened my notes to write the scorecard and found one line: "Solved it. I have no idea how." That is the short version of why strong engineers fail coding interviews. Not because they can't code. Because nothing they did survived the trip from the room to the scorecard. The interview is not the thing being graded. The document I write forty minutes later is the thing being graded, and you are not in the room when it gets read. TL;DR Strong engineers fail coding interviews mostly on signal density , not correctness. A silent correct answer scores lower than a narrated near-miss. Interviewers score 3-4 rubric axes (problem solving, coding, communication, and for senior roles, judgment) and each axis needs quotable evidence , not vibes. The decision happens in the debrief , where ambiguity defaults to no. "Lean hire" across the board is a rejection at most companies. The most common senior failure is solving a senior problem like a junior : no scoping, no tradeoffs, no failure modes, no tests. Fix it by talking in sentences your interviewer can transcribe verbatim: assumption, tradeoff, complexity, test. What do interviewers actually score in a coding interview? Not "did you get the answer." Almost every structured loop I've been part of scores a fixed rubric, and correctness is one box inside one axis. Here is roughly what the form looks like: Axis What it's really asking What lands on the scorecard Problem solving Did you scope before you built? "Asked whether input fits in memory before choosing an approach." Coding Would this survive code review? "Named things well, extracted a helper, no off-by-one." Communication Could I follow you in real time? "Told me the plan first, then coded the plan." Judgment (senior+) Do you know what breaks in prod? "Unprompted, called out the retry storm risk." Notice what every r

W. Kamau Bell is one of those people who has always just seemed to be there. From Totally Biased, to Politically Re-Active, United Shades of America, and We Need to Talk About Cosby, his blend of comedy, social commentary, and political activism has helped him stand out. He's won a Peabody and four Emmys, been […]

1. What is a Test Case? A Test Case is a set of steps, test data, conditions and expected results used to check whether a particular functionality is working correctly or not. Example: For a login page, enter a valid username and password and click Login. The expected result is that the user should successfully log in. 2. What is a Test Scenario? A Test Scenario is a high-level functionality or condition that needs to be tested. Example: "Verify Login Functionality" is a Test Scenario. Under this scenario, we can create multiple test cases like valid login, invalid password, empty username, empty password, etc. 3. What are Negative Test Cases? Negative Test Cases are used to check how the application behaves when invalid or unexpected data is given. Example: Entering an incorrect password or leaving the username field empty. The application should not crash and should show the proper error message. 4. What are Positive Test Cases? Positive Test Cases check whether the application works correctly with valid and expected input. Example: Entering a valid username and password should allow the user to log in successfully. 5. Relationship Between Test Case and Test Scenario A Test Scenario is a high-level requirement or functionality, while a Test Case contains detailed steps to test that scenario. Example: Test Scenario: Verify Login Functionality. Test Cases: Login with valid username and password. Login with invalid password. Login with empty username. Login with empty password. So, one Test Scenario can have multiple Test Cases. 6. What is Unit Testing? Unit Testing is testing individual units or components of software separately. Usually, developers perform Unit Testing. Example: If there is a function that calculates the total price, we can test that function separately to check whether it returns the correct result. 7. What is Integration Testing? Integration Testing is used to check whether two or more modules work correctly after they are combined. It mainly foc

There's something just a little bit different about FromSoftware's office in Tokyo. Like with any other successful video game studio, there's extensive security to get in the door, a minimalist lobby with framed posters from the studio's most recent releases, and a large glass display case filled with statues from ceremonies ranging from the BAFTAs […]

Proton’s CEO is a champion of encryption for everyone. So why is he going all in on un-encryptable AI?

30 React.js Interview Questions You Should Know Before Your Next Frontend Interview ⚛️ Whether you're preparing for a frontend interview or simply want to brush up on your React.js knowledge , this guide covers 30 real-world, scenario-based React interview questions that interviewers frequently ask. The goal isn't just to memorize definitions. These questions are designed to help you understand how and when to apply React concepts in real-world applications . 📌 Bookmark this article and come back to it during your next interview preparation session. 📚 What We'll Cover In this guide, we'll explore questions around: Conditional rendering API calls and side effects Form validation Performance optimization State management Component re-rendering Keys and lists Dark mode Dynamic components useEffect vs useLayoutEffect Large-list optimization And much more... 1. How do you handle conditional rendering in React? Conditional rendering allows you to render different UI based on application state or conditions. You can use standard JavaScript techniques such as: if...else Ternary operators Logical && Example { isLoggedIn ? < Dashboard /> : < Login />} 💡 Interview Tip For simple conditions, a ternary operator or && is usually sufficient. For more complex conditions, consider moving the logic outside the JSX to keep the component readable. 2. You need to fetch API data when a component mounts. What's the best way to do it? 💡 Key Concept The typical approach is to perform the API request inside a useEffect hook when the component needs to fetch data after rendering. A common pattern is: useEffect (() => { // Fetch API data }, []); The empty dependency array indicates that the effect is intended to run after the initial render. Note: In modern React applications, the best approach can also depend on the framework or data-fetching library you're using. 3. How would you handle form validation in React? A common approach is to use controlled inputs and perform validation during even

As if you needed more reason to love Carly Rae Jepsen's "Call Me Maybe" beyond its pop perfection, it is also, according to lore, the genesis for Switched on Pop, one of the best music podcasts out there. Cohosts Nate Sloan and Charlie Harding obsessively dissect pop songs, from the theory behind their musical choices […]

The version of The X-Files: I Want to Believe that premiered in 2008 was not exactly the movie co-writer / director Chris Carter intended to make. Carter wanted to bring agents Mulder and Scully back to the big screen with a grisly story about faith and the supernatural. But executives at 20th Century Fox felt […]

Imagine this: It's salary day. It's 2 PM. Millions of people across India suddenly open their UPI apps and start paying rent, sending money to family, paying credit-card bills, and shopping online. Now here's the system-design interview question: If millions of people make payments at almost exactly the same time, is every request hitting one central server? What prevents the entire payment system from freezing? At first glance, it sounds like a scaling problem. It isn't just a scaling problem. It's a combination of: horizontal scaling concurrency distributed systems database consistency retries idempotency backpressure failure isolation downstream bottlenecks And that's what makes payment systems such an interesting system-design problem. First: Don't Imagine One Giant UPI Server A common mental model looks like this: Millions of users | v +-------------+ | UPI Server | +-------------+ | v Bank If that were literally true, we'd have a pretty serious problem. One machine cannot safely process the country's entire payment traffic. Instead, think about a distributed system: Users | v +---------------+ | API / Gateway | +---------------+ / | \ / | \ v v v [S1] [S2] [S3] | | | +------+------+ | Payment Services | +--------+--------+ | | Bank A Bank B The exact implementation of a real payment network is much more complicated than this diagram, but this is the right system-design mental model . The important idea is: The system is distributed across many machines and participating institutions. Step 1: The First Problem — Traffic Spikes Let's take a concrete example. You want to pay your landlord: ₹25,000 At the same moment, millions of other people are doing something similar. Suddenly: Normal traffic: 100K requests/sec Salary day: ████████████████████████ 1M+ requests/sec The first question is: How do we handle the additional traffic? Naive Solution: One Powerful Server We could buy a massive machine. 1M requests/sec | v +---------------+ | HUGE SERVER | | 256 CPU core

Tom Vek burst onto the scene in 2005 with his album We Have Sound, which garnered a solid 7.6 from the tastemakers of the day over at Pitchfork. His undeniably catchy brand of dancy indietronica landed him an appearance on The OC and placement on the Grand Theft Auto IV soundtrack. His follow-up, Leisure Seizure, […]

So far in this mini-series, we've answered the biggest questions that confuse developers when they first encounter Design Patterns. We've learned: why SOLID isn't the final destination, why recurring design problems exist, why copying code doesn't create good design, what Design Patterns really are, how experienced engineers recognize them, and how every pattern can be understood through its Problem, Intent, Solution, and Consequences . Now it's time to answer one final question before we begin exploring the individual patterns. How should we learn Design Patterns so that we can actually use them in real-world software instead of just recognizing their names? The answer may surprise you. We're not going to learn Design Patterns the way they're usually taught. The Traditional Way of Learning Design Patterns Open almost any Design Patterns book or tutorial, and you'll often see something like this. Pattern Name ↓ Definition ↓ UML Diagram ↓ Code Example ↓ Advantages ↓ Disadvantages Technically, there's nothing wrong with this approach. But many developers finish reading the chapter and still wonder: "When would I ever use this?" That's because they learned the solution before understanding the problem. It's like learning how to use a fire extinguisher before understanding what kinds of fires it can safely put out. Knowledge without context is difficult to apply. The Way Experienced Engineers Learn Experienced engineers don't begin with the pattern. They begin with the software. They observe where the current design starts struggling. Only then do they search for a better design approach. Their thinking looks more like this. Business Requirement ↓ Design Challenge ↓ Current Design Starts Breaking ↓ Understand Why ↓ Explore Better Design ↓ Recognize a Design Pattern The pattern is never the starting point. It's the result of understanding the problem. The Learning Framework We'll Use Every pattern in this series will follow exactly the same structure. Business Problem ↓

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If you've started learning DBMS for software engineering interviews, you've probably come across terms like Functional Dependency , Attribute Closure , Candidate Key , Normalization , and Canonical Cover . For many beginners, Canonical Cover feels like another algorithm to memorize. It isn't. Before you ever learn how to compute a Canonical Cover, you should understand why it exists . This article focuses only on the Introduction and Foundations . We intentionally won't discuss the algorithm yet. What Is the Interviewer's Intent? When interviewers ask about Canonical Cover , they are usually not testing your memorization . Instead, they want to know whether you understand: How databases represent business rules Why redundant rules create problems Whether you can simplify complex dependency sets Whether you understand the foundations of normalization In interviews, Canonical Cover often appears before questions on: Normal Forms Dependency Preservation Lossless Decomposition BCNF Schema Design Interviewers are checking your understanding of database design , not your ability to recite definitions. Why Do Interviewers Ask Canonical Cover? Imagine a database contains hundreds of dependency rules. Many of those rules may: Repeat the same information Contain unnecessary attributes Be derivable from other rules A good software engineer should recognize unnecessary complexity. Canonical Cover is essentially about answering one question: "Can we represent exactly the same constraints using fewer and simpler rules?" That's why interviewers ask it. They want to see whether you appreciate: simplicity correctness maintainability efficient schema design Where Does Canonical Cover Fit Inside DBMS? Think of DBMS topics as a learning roadmap. DBMS | -------------------------------- | | Database Design Transactions | | Functional Dependencies | Attribute Closure | Candidate Keys | Canonical Cover | Normalization | 2NF → 3NF → BCNF Canonical Cover belongs to the database design portio

"A Trie isn't designed to store words. It's designed to make finding everything that shares the same beginning incredibly efficient." In the previous article, we explored a different kind of software problem. Some systems don't search using complete values. Instead, users provide only part of the information they know. The system must immediately suggest possible matches. Once you recognize that requirement, another question naturally follows. How should the system organize data so prefix searches become fast and natural? This is exactly the problem a Trie solves. Think About a Dictionary Imagine opening a physical dictionary. Suppose you're looking for the word: Application Do you start reading from page one? Of course not. You first go to the words beginning with: A Then you narrow further. Ap Then: App Every additional letter reduces the search space. A Trie works in a very similar way. Instead of repeatedly searching through every word, it follows the characters one by one. What Is a Trie? A Trie is a tree-like data structure where each node represents a character. Words that begin with the same characters share the same path. Consider these words. car card care cart A Trie stores them like this. Root ↓ c ↓ a ↓ r ├── end ├── d → end ├── e → end └── t → end Notice something interesting. The prefix: car is stored only once. Every longer word simply continues from that shared path. Every Data Structure Answers a Different Question By now we've seen several data structures, each solving a different design problem. A HashMap asks: Where is this exact object? A Heap asks: Which item has the highest priority? A Queue asks: Which task should happen next? A Stack asks: What is the current working context? A Trie asks: What begins with these characters? Choosing the right data structure starts with identifying which question your software needs to answer. Inserting a Word Imagine inserting: cat The Trie creates a path. Root ↓ c ↓ a ↓ t Now insert: car The beginning alread