Backend · Senior · Theory

In production, a query against a 200-million-row orders table suddenly started taking seconds instead of milliseconds. How would you investigate, and what can you do with indexes?

~4 min by voice

How to approach it

This checks whether the candidate can systematically diagnose query degradation on a large table: from finding the query and its execution plan to the reasons the plan changed. Second, whether they understand how to design an index properly, roll it out safely in production, and what that index costs.

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Topics

indexes query performance

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Answer by voice

The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.

Best with headphones · ~4 min