Saidul Islam Rajib Saidul Islam Rajib

Tagged “backend”

2 posts found.

Jul 10, 2026· 2 min read ·6 views

Idempotency keys, or how to make retries safe

The network failed after the charge but before the response — now what

Key takeaways
  • A timeout tells you nothing about whether the work happened.
  • Idempotency is a property of the endpoint, not of the client.
  • Store the key with the result, not just the key.

A client calls POST /payments . The charge succeeds. The response times out on the way back. The client has no idea whether it worked. If it retries, you might charge twice. If it…
api-designbackenddistributed-systems
Jul 9, 2026· 2 min read ·9 views

The N+1 query problem, and why your ORM hides it

One query for the list, then one more per row, forever

Key takeaways
  • Loop bodies that touch the database are the smell.
  • Log your SQL in development — the count is the tell.
  • Fix it by fetching related rows in one query, not by caching the symptom.

You fetch 50 posts. Then, for each one, you read its author. That is 1 + 50 = 51 queries where 2 would do. It looks harmless because each individual query is fast. The problem is t…
databasesbackendperformance