If no precedence relation exists, both can be voted on concurrently.
2.
Local transactions can be always committed concurrently ( even if a precedence relation exists, unlike CO ).
3.
:In the "'precedence graph "'transactions are nodes and precedence relations are directed edges.
4.
Thus information distribution is needed ( e . g ., precedence relations, lock information, timestamps, or tickets ).
5.
The sequences or " paths " of morphisms for which there is no inverse morphism, could then be interpreted as defining horismotic or chronological precedence relations.
6.
A marking of the cell indicates a directed link between two elements and can represent design relations or constraints between product components, communication between teams, information flow or precedence relations between activities.
7.
Thus CO ( with its variants ) is the only general technique that does not require the typically costly distribution of local concurrency control information ( e . g ., local precedence relations, locks, timestamps, or tickets ).
8.
If a precedence relation ( conflict ) exists between two transactions, then the second will not be voted on before the first is completed ( either committed or aborted ), to prevent possible commit order violation by the atomic commitment protocol.
9.
A distinguishing characteristic of the CO solution to distributed serializability from other techniques is the fact that it requires no conflict information distributed ( e . g ., local precedence relations, locks, timestamps, tickets ), which makes it uniquely effective.
10.
:"'Conflict-serializability "'is defined by equivalence to a serial schedule ( no overlapping transactions ) with the same transactions, such that both schedules have the same sets of respective chronologically ordered pairs of conflicting operations ( same precedence relations of respective conflicting operations ).
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