Causal consistency
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Causal consistency is one of the consistency models used in the domain of the concurrent programming (e.g in distributed shared memory, distributed transactions etc).
A system provides causal consistency if writes that potentially are causally related are seen by every node of the system in the same order. Concurrent writes may be seen in different order by different nodes. This is weaker than sequential consistency, which requires that all nodes see all writes in the same order.
When a node performs a read followed later by a write, the two operations are said to be causally related because the value stored by the write may have been dependent upon the result of the read. Similarly, a read operation is causally related to an earlier write that stored the data retrieved by the read. Operations that are not causally related are said to be concurrent.
