A release that causes data loss

System design scenarios Senior Swift 5.0+ iOS 17+ Reviewed By Alok Singh

Order the steps

Order the response.

  • Pause the phased release and turn off related flags
  • Reproduce and find the root cause
  • Ship a hotfix that disables the faulty path
  • Recover data where possible and tell affected users
  • Add regression tests and migration safeguards
Hint 1 of 1

Contain before you investigate.

Choose an answer, then open Show answer below to check it.

Show answer

Answer: A C B D E

  1. Pause the phased release and turn off related flags Stop more users from being affected.
  2. Ship a hotfix that disables the faulty path Protect data for users already on the release.
  3. Reproduce and find the root cause Diagnose with logs and the failing scenario.
  4. Recover data where possible and tell affected users Restore trust and data.
  5. Add regression tests and migration safeguards Prevent a repeat.

30-second answer

Stop the spread first: pause the phased release, turn off any flags involved, and stop the server from accepting destructive changes if relevant. Protect what remains by shipping a hotfix that disables the faulty path. Reproduce with diagnostics to find the root cause, recover users' data from server copies or backups where possible, tell affected users honestly, and add regression tests and migration safeguards.

Practise saying it · 60 s. No recording, just a timer

Walk through a data-loss incident.

Say your answer out loud, then check which of these points you covered:

  • Contain
  • Protect
  • Root cause
  • Recover and communicate
  • Prevent

Deep dive

Phased release limits the blast radius.

Keep server-side history or soft deletes to make recovery possible.

Migrations should never delete the old data until the new data is verified.

Coordinate support messaging early.

Common mistakes

  • Investigating for days while the rollout continues.
  • Silent fixes without telling affected users.

Senior take & follow-ups

Seniors contain, protect, recover and prevent, and communicate throughout.

Follow-up questions

Think of your answer first, then open the hint.

  1. How do you limit damage?

    Show hint

    Pause the release and turn off flags.

  2. How do you make recovery possible next time?

    Show hint

    Keep old data until migrations are verified, plus server history.

Related questions

Suggest a fix if something here is wrong or out of date.