{"id":"ssi-extends-mvcc-with-dependency-tracking","text":"`SSIDatabase` adds a `_dependency_graph` and `_predicate_locks` on top of MVCC to detect read-write conflicts (write skew) that basic snapshot isolation permits","truth_value":"IN","source":"entries/2026/05/29/topic-mvcc-snapshot-isolation.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{"example":"self._dependency_graph = {}  # tx_id -> set of tx_ids\n# on read:\nif writer_tx_id is not None:\n    self._dependency_graph[tx.tx_id].add(writer_tx_id)"},"explanation":{"steps":[{"node":"ssi-extends-mvcc-with-dependency-tracking","truth_value":"IN","reason":"premise"}]}}