Practical insights on APIs, databases, performance tuning, and the craft of building reliable server-side systems.
Polling wastes 99% of its requests asking a question whose answer is 'nothing new.' Webhooks flip the direction and eliminate that waste — while handing you a public endpoint, unverified callers, duplicate deliveries, and failures you can't see. Here's the honest comparison.
The client's network dropped right after they hit 'Pay.' Did the charge go through? They retry. Now you might charge them twice. Idempotency keys are how you let clients retry safely without double-processing — and they're more subtle than they look.
Most developers know indexes make queries fast. Few understand why. This post breaks down B-Tree indexing, query planning, and the exact mechanics that turn a 2-second query into a 2ms one.