Backend guides
Connect how clients talk to your server, how you model data, and how you keep services reliable and safe.
What is the N+1 query problem in ORMs and APIs?
One query for a list, then N more for each item: a classic performance bug in data loaders.
ormperformancesql
How should backend apps use environment variables and secrets?
12-factor style config, .env in dev, and never committing API keys to git.
configsecuritydevops
What is rate limiting in APIs and when do you return 429?
Protect the service, fair use, and abuse: tokens, sliding windows, and headers.
httpreliabilitysecurity
What is a database index and when does an index speed up a query?
B-tree style structures help the engine find rows without scanning every page - at a write cost.
sqlperformancepostgres
What are database migrations and how do teams apply schema changes safely?
Versioned SQL or DSL changes, up/down, and why you never hand-edit production schema only in a GUI on Fridays.
sqlmigrationsdevops
What is an idempotency key in payment and write APIs?
Let clients safely retry POST: the server stores a fingerprint of the first outcome and returns the same result for duplicates.
httpreliabilitypayments