How do you handle two requests trying to update the same record at the same time?

What the interviewer is looking for

• This question tests performance & concurrency. Explains race conditions, locking or optimistic concurrency, and profiles before optimising.
• Strong answers: Recognising the race condition, transactions, row locks or optimistic version checks, unique constraints, and clear handling for the losing request.
• Likely follow-up: When would you prefer optimistic locking over pessimistic locking?

Another way it may be asked: Two people try to book the last concert ticket at the same moment. How do you make sure only one gets it?

A structure to follow: Answer, explain, example, limits

1. Step 1

   Answer

   Give your direct answer in the first sentence so the interviewer knows where you are going.

2. Step 2

   Explain

   Say how it works or why you would do it that way, in plain words before jargon.

3. Step 3

   Example

   Anchor it in something you have actually done or seen, with the detail that shows hands-on experience.

4. Step 4

   Limits

   Say when your approach would not be the right one. It shows judgement.

This is guidance on shape, not a script. Use your own real experience and facts; never invent details to fill a gap. See the STAR guide and answer frameworks.

Common slips

• Reciting a definition without showing you have applied it.
• Using terms you cannot explain if asked a level deeper.
• Claiming experience beyond what you can discuss in detail.

How to practise it

Say the answer in 90 seconds, then answer the follow-up as if it were a new question.

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