tag: Consistency

Notes Causal consistency and logical timestamps Logical Timestamps(Lamport timestamps) don’t imply causal consistency 13) Causal Consistency, COPS#Causal

Notes Requirements for consistencies Linearizability Global ordering Completion to Invocation globally Sequential Global ordering Completion to Invocation per client Causal Completion to invocation per client Write and then later read dependency Transitivity for 1) #Causal and 2) #Causal Fork-join Causal Eventual

Notes Dynamo is similar to a Distributed Hash Table meaning it uses consistent hashing. Dynamo is called a zero-hop DHT because each node has enough information about the whole consistent hashing ring that it can directly transfer any client to the server responsible for serving that key. Causes for the system not being linearizable Initializing replication factor but not having the same number of writes/reads Membership changes Discovery of membership changes is at different times, due to gossip protocol, causing writes to happen at different servers than intended. When key exchanges are happening and data is being written to the old server. Vector Clock