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64 docs tagged with "interview"

College vs Production: Database Locking & MVCC

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College vs Production: Database Normalization (3NF vs Denormalization)

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College vs Production: Why Recursion CRASHES in Production

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College vs Production: Why SHA-256 Fails for Passwords

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Forward Proxy vs Reverse Proxy: The Only Rule You Need

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How Bloom Filters Actually Work

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How Databases Handle Connection Spikes

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How Message Queues Handle Traffic Spikes

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How SYN Cookies STOP Server Crashes

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How to Scale WebSockets Across Multiple Servers

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Mutex vs. Spinlock: Why Sleeping Kills Performance

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Non-Repeatable Read vs Phantom Read

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Search Autocomplete: Debounce vs Throttle

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Why 0.1 + 0.2 ≠ 0.3 in Programming

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Why 1 + 4 + 1 = 12 Bytes in C/C++ (Struct Padding)

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Why 2GB Free RAM CAN'T Allocate 200MB (External Fragmentation)

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Why 32-Bit Systems CANNOT Use 8GB RAM

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Why APIs Use Idempotency Keys (Prevent Double Payments)

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Why Array Traversal is 10x FASTER Than Linked Lists

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Why Base Destructors MUST Be Virtual in C++

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Why Can't One Process Access Another's Memory?

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Why ChatGPT Uses SSE Instead of WebSockets

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Why CPUs Reorder Code Behind Your Back (Memory Barriers)

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Why Distributed Systems Use Consistent Hashing

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Why DNS is Super Fast the Second Time

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Why Do Database Indexes Slow Down INSERTs?

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Why Do Databases Use B+ Trees Instead of Binary Search Trees?

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Why Do Databases Use Write-Ahead Logging (WAL)?

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Why Do Deadlocks Happen?

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Why Do Page Faults Happen?

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Why Do Systems Use Rate Limiters?

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Why Do Zombie Processes Exist?

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Why Docker Boots in Milliseconds While VMs Take Minutes

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Why Does Linux Use Copy-on-Write (COW)?

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Why Does TCP Use a Sliding Window?

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Why Does Virtual Memory Make Computers Faster?

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Why Dynamic Arrays Double Their Size (ArrayList / std::vector)

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Why Epoll is 100x Faster Than Select (I/O Multiplexing)

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Why Expired Cache Keys CRASH Databases

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Why HashMap Capacity is ALWAYS a Power of 2

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Why HashMaps Switch to Trees at 8 Collisions

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Why Is a Process Switch Slower Than a Thread Switch?

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Why is HTTPS More Secure Than HTTP?

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Why is TCP Reliable but UDP Isn't?

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Why is UDP Used for Video Calls Instead of TCP?

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Why Isn't a 2-Way Handshake Enough in TCP?

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Why LIKE '%term' Destroys Database Performance

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Why Low-Priority Threads FREEZE High-Priority Tasks

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Why malloc(1GB) DOES NOT Consume 1GB RAM

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Why NoSQL Sacrifices ACID for High Availability

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Why NULL = NULL is FALSE in SQL

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Why Prefer Composition Over Inheritance?

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Why Priority Queues Use Heaps Instead of Arrays

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Why Production Systems Separate Reads & Writes

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Why QuickSort beats MergeSort (O(N²) vs O(N log N))!

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Why Random UUIDs SLOW DOWN Your Database

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Why Running Out of RAM Freezes Your CPU (Thrashing)

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Why Sending 1 Reads as 16,777,216 Over Sockets (Endianness)

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Why Sorted Arrays Run 6x FASTER (Branch Prediction)

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Why Stack Memory is 10x FASTER Than Heap

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Why Static Functions Cannot Access this in C++

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Why Strings are IMMUTABLE (Python, JS, Java)

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Why TRUNCATE is 100x Faster Than DELETE

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Why User Apps CANNOT Touch Hardware (CPU Protection Rings)

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