Study Logs

Notes on backend engineering and lessons from production.

Topics

Recent writing

  1. Backend Engineering

    Idempotency beyond the request

    What happens when a retry lands after the work completed but before the response arrived?

  2. Production Gotchas

    Where did the timeout come from?

    Work backward from the first deadline that actually expired.

  3. Databases

    Reading a query plan from the bottom up

    Find the earliest estimate that diverges from the rows the database actually saw.

  4. Distributed Systems

    What a worker lease actually protects

    A worker can resume after its lease expires. The write path needs to account for that.