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Consistent hashing is at the core of many P2P protocols. It evenly distributes the keys over the nodes, thereby enabling logarithmic routing effort 'with high probability'. However, consistent hashing incurs unnecessary overhead as shown in this paper.By removing consistent hashing from Chord, we derived a protocol that has the same favorable logarithmic routing performance but needs less network hops for updating its routing table. Additionally, our Chord # protocol supports range queries, which are not possible with Chord. Our empirical results indicate that Chord # outperforms Chord even under high churn, that is, when nodes frequently join and leave the system.

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Building consensus sequences based on distributed, fault-tolerant consensus, as used for replicated state machines, typically requires a separate distributed state for every new consensus instance. Allocating and maintaining this state causes significant overhead. In particular, freeing the distributed, outdated states in a fault-tolerant way is not trivial and adds further complexity and cost to the system. In this paper, we propose an extension to the single-decree Paxos protocol that can learn a sequence of consensus decisions 'in-place', i.e. with a single set of distributed states. Our protocol does not require dynamic log structures and hence has no need for distributed log pruning, snapshotting, compaction, or dynamic resource allocation. The protocol builds a fault-tolerant atomic register that supports arbitrary read-modify-write operations. We use the concept of consistent quorums to detect whether the previous consensus still needs to be consolidated or is already finished so that the next consensus value can be safely proposed. Reading a consolidated consensus is done without state modifications and is thereby free of concurrency control and demand for serialisation. A proposer that is not interrupted reaches agreement on consecutive consensus decisions within a single message round-trip per decision by preparing the acceptors eagerly with the previous request.