Adya’s formalization of transactional isolation levels provides a more thorough summary of the preventative interpretation of the ANSI levels, defining serializability as the absence of four phenomena. Serializability prohibits:
Here w denotes a write, r denotes a read, and subscripts indicate the transaction which executed that operation. The notation “…” indicates a series of micro-operations except for a commit or abort. P indicates a predicate.
As Adya notes, the preventative interpretation of the ANSI specification is overly restrictive: it rules out some histories which are legally serializable.
ligurio
commented
3 years ago
Adya’s formalization of transactional isolation levels provides a more thorough summary of the preventative interpretation of the ANSI levels, defining serializability as the absence of four phenomena. Serializability prohibits:
Here
wdenotes a write,rdenotes a read, and subscripts indicate the transaction which executed that operation. The notation “…” indicates a series of micro-operations except for a commit or abort.Pindicates a predicate.As Adya notes, the preventative interpretation of the ANSI specification is overly restrictive: it rules out some histories which are legally serializable.