UAUjjwal Agarwalinguidetodevelopment.hashnode.dev·11h ago · 7 min readWhat Actually Happens Inside PostgreSQL When You UPDATE a Row? Most developers think of a PostgreSQL table like this: users ---------------- id | age ---------------- 1 | 25 2 | 31 3 | 42 Then we run: UPDATE users SET age = 30 WHERE id = 1; The obvious menta00
AUAman Upadhyayindev-jedi.hashnode.dev·13h ago · 7 min readSerialization and Deserialization in BackendIn the previous blogs, we've talked about HTTP, requests and responses, and how routing helps a backend decide where an incoming request should go. But there's another interesting question here. Let's00
KGKunal Guptainkunalforked.hashnode.dev·1d ago · 11 min readPrefect on Kubernetes: ExplainedFlows, tasks, deployments, work pools, workers, and what actually happens to a pod from the second it's born to the second it dies. Quickly, what is Prefect? Say your app's UI has a button - "Run Repo10
LDLakshay Dhoundiyalinlakshaydhoundiyal.hashnode.dev·1d ago · 12 min readHow Does Uber Find Your Driver in Seconds? The System Design Behind UberYou open Uber. Enter your destination. Tap “Confirm Ride.” 🚗 A few seconds later, your screen shows: “Driver found.” You can see the driver's name, vehicle, location, and estimated arrival time. It f10
AMAkshay Mukadaminakshaym.hashnode.dev·19h ago · 7 min readWhy We Chose Redis Streams and Redis Queues Over Kafka 1I will output the finalized entire blog post right away. No additional information is requested. I'll just present the complete final post you've approved, ready for copy/pasting. Choosing Redis Over00
DPDevesh Parmarinbackend-bytes.hashnode.dev·20h ago · 7 min readThe Bug That Sent Two Delivery Partners to the Same OrderImagine you're the backend engineer at Swiggy, working on the dispatch service that assigns incoming orders to nearby delivery partners. It's peak dinner hour. A restaurant marks an order ready for pi00
PEPaymos Engineeringinpaymos-engineering.hashnode.dev·22h ago · 7 min readDuplicate webhooks are the contract, not the bugA payment webhook is not a message. It is a delivery attempt. Paymos makes 11 of them per event: one initial call and ten retries, spaced 1m, 2m, 4m, 8m, 16m, 32m, 1h, 2h, 4h, and 8h, for a window of 00
KGKunal Guptainkunalforked.hashnode.dev·1d ago · 5 min readThree Restaurants, One Kitchen: What Broke When it ScaledContinuation of One Socket, a Thousand Waiters, turns out the trick works great, right up until you run more than one copy of it. Worked perfectly with one pod. The moment we scaled to three, jobs sta10
RSRajaram Sinrajaram0203.hashnode.dev·1d ago · 9 min read🗄️ Database Fundamentals — SQL vs NoSQL, When to Use Which⏱️ 10–12 min read · 🎯 Beginner · 📚 Part 13 of 20 👉 Missed Part 12? Webhooks — Event-Driven APIs 🎉 Welcome to Section 4 — Databases & SQL Parts 1 through 12 covered how APIs talk to clients and to00
NSNilay Shahaneincuriousnilay.hashnode.dev·1d ago · 6 min readWhat LLM Parameters Actually Do (I Didn’t Even Know Half of These Existed)When I built my AI financial assistant, I was focused on getting the pipeline working: user query → retrieval → LLM → response. The model was responding correctly, but I realized something embarrassin10
