SSI (Serializable Snapshot Isolation)

RU: SSI (Serializable Snapshot Isolation)

Serializable Snapshot Isolation — the algorithm behind PostgreSQL's SERIALIZABLE level since version 9.1. SSI runs snapshot isolation but additionally tracks read-write antidependencies between transactions using SIREAD locks; when it detects a dangerous structure — a pivot transaction that has both an incoming and an outgoing rw-antidependency (T1 --rw--> Tpivot --rw--> T2) — it aborts one transaction to prevent any serialization anomaly, including write skew.