Code RoomProfile updates show stale reads
MediumPrep Room Coding #2582

Profile updates show stale reads

On-callDatabases & SQLDistributed systemsMid–Senior~30 min

After a database failover at 15:20, users intermittently see stale data: they update a profile, the save succeeds, but a reload sometimes shows the old value for ~10s. Dashboards: a MySQL primary failover happened at 15:20 (old primary had a hardware fault); your app reads from a pool of replicas and writes to the primary; replication lag on two replicas spiked to 8-12s right after the failover; reads are randomly load-balanced across replicas including the lagging ones. No app deploy. 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.