Questions 201–238 of 238

  1. How do you identify a bottleneck across an API and database, and verify that the fix worked?

    Asked once · last asked Oct 20 · Scenario · Senior

  2. Assume the outbox backlog grows to millions of rows. How would you design storage, retention, and publisher workers so the outbox queries stay fast and don't overload the primary database?

    Asked once · last asked Oct 22 · Design · Senior

  3. Can you describe a nontrivial database query or optimization and explain how you would approach it?

    Asked once · last asked Oct 23 · Behavioral · Senior

    Other ways it was asked
    • “Can you give an example of a complex or nontrivial database query or optimization you worked on?”

  4. Can a database index cover one column or multiple columns?

    Asked once · last asked Apr 4 · Concept · Junior

  5. How can you check the size of a database index?

    Asked once · last asked Apr 15 · Tooling · Mid-level

  6. What does it mean for a database to be over-indexed?

    Asked once · last asked Apr 15 · Concept · Mid-level

  7. After limiting database queries and checking for a recent change or deployment, what would you do next?

    Asked once · last asked Apr 17 · Scenario · Senior

  8. What are column statistics in a data table, and what are they used for?

    Asked once · last asked Apr 17 · Concept · Mid-level

  9. Are column statistics computed automatically, or do you need to run a command to compute them?

    Asked once · last asked Apr 17 · Concept · Mid-level

  10. What is a B+ index?

    Asked once · last asked May 2 · Concept · Junior

  11. What is a join index?

    Asked once · last asked May 2 · Concept · Mid-level

  12. Why do you need to optimize queries?

    Asked once · last asked May 22 · Concept · Junior

  13. What is database partitioning?

    Asked once · last asked May 25 · Concept · Junior

  14. How would you investigate a database issue that is causing an application problem?

    Asked once · last asked Jun 18 · Scenario · Mid-level

  15. What database optimization techniques can improve performance besides adding indexes?

    Asked once · last asked Jun 18 · Concept · Mid-level

  16. What is an index, and what is the purpose of it?

    Asked once · last asked Jul 16 · Concept · Junior

  17. How do you create database indexes in an application?

    Asked once · last asked Jul 16 · Tooling · Mid-level

  18. How would you validate a database performance hypothesis by comparing query execution plans and their estimated costs?

    Asked once · last asked Jul 22 · Scenario · Senior

  19. Can you create an index on a columnar database?

    Asked once · last asked Jul 29 · Concept · Junior

  20. How do you determine whether data volume is causing a database performance problem?

    Asked once · last asked Aug 4 · Scenario · Mid-level

  21. Is there a maximum number of columns a table can have before performance problems occur?

    Asked once · last asked Aug 4 · Concept · Junior

  22. How do you optimize SQL queries in large enterprise databases?

    Asked once · last asked Aug 4 · Scenario · Mid-level

  23. How would you verify that a SQL query returns the correct results and an appropriate number of records?

    Asked once · last asked Aug 11 · Scenario · Mid-level

  24. How do you assess and improve database performance?

    Asked once · last asked Aug 12 · Scenario · Mid-level

  25. Which type of index, clustered or nonclustered, would you choose for faster data retrieval?

    Asked once · last asked Aug 12 · Scenario · Mid-level

  26. Can you tell me about clustering methods in SQL?

    Asked once · last asked Sep 2 · Concept · Mid-level

  27. What would you do if a query was taking a very long time to run?

    Asked once · last asked Sep 9 · Scenario · Mid-level

  28. How would you retrieve rows 200 through 300 from a paginated SQL query?

    Asked once · last asked Sep 10 · Concept · Junior

  29. How many indexes can you create on a SQL table?

    Asked once · last asked Sep 21 · Concept · Junior

  30. Can you explain what a clustered unique key is?

    Asked once · last asked Sep 25 · Concept · Junior

  31. What is pagination in PostgreSQL?

    Asked once · last asked Sep 30 · Concept · Junior

  32. How can a composite key help you select records efficiently?

    Asked once · last asked Oct 6 · Concept · Mid-level

  33. How would you use OFFSET to retrieve paginated records?

    Asked once · last asked Oct 6 · Concept · Mid-level

  34. What kind of composite key would you use for paginating user records?

    Asked once · last asked Oct 6 · Scenario · Senior

  35. Why use an index in SQL?

    Asked once · last asked Oct 7 · Concept · Junior

  36. What is the query planner in PostgreSQL?

    Asked once · last asked Oct 7 · Concept · Mid-level

  37. What would you check to improve product catalog query performance?

    Asked once · last asked Oct 21 · Scenario · Mid-level

  38. What does PostgreSQL call a deduplicated B-tree tuple?

    Asked once · last asked Oct 24 · Concept · Senior

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More SQL interview questions

How this list is made

Every question here was asked by a real interviewer in a real job interview that a candidate ran MeetAssist in. After the call, the interviewer's questions are pulled from the transcript. Practice sessions, tests, exams and anything that was not a job interview are dropped.

Questions are rewritten so they make sense on their own: names of people, employers and clients are removed, and speech-to-text mistakes are fixed. Small talk, logistics and questions about one candidate's own résumé are left out. Rephrasings of the same question are merged, and the count is the number of different interviews it came up in.

The interviews come from candidates who use MeetAssist, so they lean towards software, data and AI roles: the shares describe these interviews, not every SQL interview. Answers to the most asked questions are written and checked by an editor; a "common mistake" is shown only when reviews of real answers in these interviews show it, with the count.

612 interviews, 357 candidates, Nov 2025 to Oct 2026. Updated every month with new interviews.