Code RoomMigration lock blocks writes
HardPrep Room Coding #3080

Migration lock blocks writes

On-callDatabases & SQLReliability & on-callSenior~20 min

A deploy ran a database migration (adding a column or index) and it's holding a long lock on a large table — writes are blocked and the app is timing out. How do you respond?

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 20 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.