Question library
Questions from real interviews. Drill any of them by voice in a couple of minutes, with an interviewer, a score and feedback.
You're told that one database query has started running very slowly. How would you look for the cause?JuniorA query that used to run in milliseconds now takes seconds after the table grew to tens of millions of rows. How would you investigate, and what can you do about it?Mid-levelThe orders list page has started taking several seconds to load, and in the logs you see hundreds of near-identical SQL queries per HTTP request. What's going on, and how would you fix it?Mid-levelIn 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?Senior