Question
A feature-store service packs each user's float32 feature vector into a fixed-width binary column and reads it back on every scoring request. At 15:00 a deploy bumped the serialization helper to a new internal library. No errors, no latency change. By 17:00, ML eng reports that scores for users who were *re-written* after 15:00 are wildly off (e.g. a churn probability of 0.02 reads back as ~3.2e38), while users not touched since the deploy score normally. Dashboards: write rate normal, deserialize error rate flat at 0. Context: the new library defaults to little-endian packing; the reader still assumes big-endian (the old default). How do you triage, stop further corruption, and recover the affected vectors?
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.