Date function prevents index usage
Review this SQL query that powers a daily-signups report over a 40M-row table.
There is a btree index on `users(created_at)` and one on `users(email)`.
What a strong answer looks like
Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix, specific and kind.
0:00 of about 20 min
Mark a line and say what kind of problem it is.0 findings
1SELECT user_id, email
2FROM users
3WHERE DATE(created_at) = '2026-06-20'
4 AND LOWER(email) LIKE '%@acme.com'
5ORDER BY created_at DESC;
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.