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For user a, changes are(v1,upsert,Ada),(v3,delete,null),(v2,upsert,Amy). User b has(v1,upsert,Bo). Versions are unique and authoritative; arrival order is as listed. Write a current-state query and describe safe incremental behavior.
1Give yourself 5 minutes
2Answer out loud, not in your head
3Then compare with the answer below
0
Reference answer
Then expect these follow-ups
How would you handle a delete followed by a legitimate recreate at a higher version?
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