335Consistency Management in Cloud Storage Systems
concurrently do not share a causality relation. Therefore, causal consistency does
not order concurrent operations. In [27,28], two operations, a and b, have a potential
causality if one of the two following conditions are met: a and b are executed in a
single thread and one operation execution precedes the other in time, or if b reads a
value that is written by a. Moreover, a causality relation is transitive. If a and b have
a causal relation, b and c have a causal relation as well, then a and c have a causal
relation.
10.3.4.2 Updates Conict Handling
In [28], a model that combines causal consistency and convergent conict handling
is presented and called causal+. Since concurrent operat ...