{"id":"first-committer-wins-on-write-conflict","text":"When two concurrent transactions write the same key, the first to call `commit()` succeeds and the second is aborted automatically","truth_value":"IN","source":"entries/2026/05/29/topic-mvcc-snapshot-isolation.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{"example":"for key in tx.write_set:\n    for other_id in self._committed:\n        other = self._transactions[other_id]\n        if key in other.write_set and other.tx_id > tx.start_timestamp:\n            tx._status = \"aborted\"\n            return False  # first committer wins"},"explanation":{"steps":[{"node":"first-committer-wins-on-write-conflict","truth_value":"IN","reason":"premise"}]}}