Editing Consistency model (section)

== Session guarantees ==

These 4 consistency models were proposed in a 1994 paper. They focus on guarantees in the situation where only a single user or application is making data modifications.<ref>{{cite book |last1=Terry |first1=Douglas B. |last2=Demers |first2=Alan J. |last3=Petersen |first3=Karin |last4=Spreitzer |first4=Mike J. |last5=Theimer |first5=Marvin M. |last6=Welch |first6=Brent B. |title=Proceedings of 3rd International Conference on Parallel and Distributed Information Systems |chapter=Session guarantees for weakly consistent replicated data |date=1 October 1994 |pages=140–150 |chapter-url=https://www.cs.cornell.edu/courses/cs734/2000FA/cached%20papers/SessionGuaranteesPDIS_1.html |publisher=IEEE Computer Society Press|doi=10.1109/PDIS.1994.331722 |isbn=0-8186-6400-2 |s2cid=2807044 }}</ref>

=== Monotonic read consistency ===
If a process reads the value of a data item x, any successive read operation on x by that process will always return that same value or a more recent value.<ref name="Replica" />

=== Monotonic write consistency ===

A write operation by a process on a data item X is completed before any successive write operation on X by the same process.<ref name="Replica" />

=== Read-your-writes consistency ===

A value written by a process on a data item X will always be available to a successive read operation performed by the same process on data item X.<ref name="Replica"/>

=== Writes-follows-reads consistency ===

A write operation by a process on a data item x following a previous read operation on x by the same process is guaranteed to take place on the same or a more recent value of x that was read.<ref name="Replica" />