Chapter 8 concept map Chapter 8 Map — Transactions at a Glance promises levels versions races 3 roads all-or-nothing blocking exactly-once TRANSACTIONS all-or-nothing units ACID promises, loosely kept Isolation levels read committed to serial MVCC versions plus visibility Anomalies skew, phantom, lost Serializability serial, 2PL, SSI Atomic commit prepare, vote, decide In-doubt plus XA blocking, needs the log Idempotency exactly-once, no 2PC Promises on top break under races on the sides; distribution below needs atomic commit or idempotency.