Meridian Line's retention policy requires that PII in safety incident narratives be permanently deleted five years after the incident is closed. The narratives live in a Delta table in Unity Catalog that also feeds a Vector Search index. What best satisfies this requirement in a way that is actually verifiable over time?

Meeting a retention requirement in a way that is actually verifiable means the deletion has to be automated and has to happen at the source of truth, so a scheduled job that purges eligible records from the Delta table on the stated retention schedule is the correct mechanism, and because Vector Search Delta Sync indexes track their source table, that deletion needs to propagate to the index rather than leaving stale PII-bearing vectors behind after the source record is gone. Manual, memory-dependent deletion is exactly what a retention policy requirement is trying to eliminate, it is neither reliable nor auditable, and it is trivially easy for it to simply not happen on schedule. A table comment documents intent but enforces nothing, it does not delete data, and it would not satisfy an auditor asking to see evidence the policy is actually being executed. Deleting only from the index while leaving the source Delta table untouched fails the requirement at its root, since the source table remains the record of truth containing the PII, and a Delta Sync index that is rebuilt or resynced would simply reintroduce the deleted vectors from the still-present source rows. Exam framing: retention enforcement has to be automated at the governed source table, with downstream synced artifacts kept consistent, not handled ad hoc or only at the index layer.