Replica replay lag growing
Users report seeing stale data — they update a setting, refresh, and the old value comes back, intermittently. Your app reads from three async streaming replicas behind a load balancer and writes to the primary. `pg_stat_replication` shows replica-2 with `replay_lag` of 45 seconds while the other two are sub-second. The primary is healthy. A bulk backfill job started 20 minutes ago on the primary, and replica-2 sits in a different AZ. Disk and CPU on replica-2 look fine but `replay_lag` keeps growing. 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 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.