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Multiversion Concurrency Control

Snapshot Isolation

MVCC implementations:

Isolation level	Oracle	Postgres < 9.1	Postgres ≥ 9.1
REPEATABLE READ	Allows phantoms (?)	Serialization anomalies (SI)	Serialization anomalies (SI)
SERIALIZABLE	Serialization anomalies (SI)	Serialization anomalies (SI)	True serializability (SSI)

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