Useful small bridge example. Two tests I'd add before using it across accounts: (1) give two servers the same numeric login and confirm the rows stay separate, so the key should include server; (2) change every copied account field and confirm the conflict branch updates each one. One field in the INSERT is missing from the UPDATE. Also, a single upsert keeps only the latest snapshot, not an audit history. If compliance needs changes over time, store timestamped observations separately and reconcile gaps after a disconnect.