Skip Graphs

TL;DR

Skip graphs are a resilient distributed data structure based on skip lists, enabling efficient, fault-tolerant search and maintenance in peer-to-peer systems with node failures.

Contribution

This paper introduces skip graphs, a novel distributed data structure that combines the functionality of balanced trees with high fault tolerance for peer-to-peer networks.

Findings

Skip graphs tolerate a large fraction of node failures without losing connectivity.

Construction, insertion, search, and repair algorithms are simple and effective.

Skip graphs outperform hash tables by supporting key-ordered queries.

Abstract

Skip graphs are a novel distributed data structure, based on skip lists, that provide the full functionality of a balanced tree in a distributed system where resources are stored in separate nodes that may fail at any time. They are designed for use in searching peer-to-peer systems, and by providing the ability to perform queries based on key ordering, they improve on existing search tools that provide only hash table functionality. Unlike skip lists or other tree data structures, skip graphs are highly resilient, tolerating a large fraction of failed nodes without losing connectivity. In addition, constructing, inserting new nodes into, searching a skip graph, and detecting and repairing errors in the data structure introduced by node failures can be done using simple and straightforward algorithms.