Connection pool exhaustion after autoscale
A fleet of 60 stateless API pods (Node.js) each holds a Postgres pool of 20 connections. After an autoscaling event scaled the fleet from 30 to 60 pods during a traffic spike, the database starts rejecting new connections with 'FATAL: sorry, too many clients already' (Postgres max_connections = 500). API error rate spikes. The DBA refuses to raise max_connections further because each Postgres backend costs ~10MB and CPU context-switching is already high. Triage and propose both the immediate fix and the right architecture.
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 35 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.