MongoDB CPU maxes after deploy
At 15:00 your MongoDB primary's CPU hits 95% and stays there; query latency across the whole app degrades, not just one feature. mongostat shows a surge in scanned documents far exceeding documents returned, the page-fault and disk-read rate is up, and the working set no longer fits in RAM. A product change last week added a new filter on an existing collection (filtering by a 'region' field). No index was added for it. Traffic is normal. How do you triage and mitigate?
What a strong answer looks like
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.
0:00 of about 30 min
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.