Although graph-databases have been assuming an increasing relevance in applications that exhibit strong dependability requirements, including tolerance to malicious faults, few works have addressed Byzantine fault tolerance in this particular context, and previous attempts suffer from lack of flexibility and poor performance. This article describes and evaluates Fireplug, a flexible architecture to build robust geo-replicated graph databases. Fireplug can be configured to tolerate from crash to Byzantine faults, both within and across different datacenters. Furthermore, Fireplug is robust to bugs in existing graph database implementations, as it allows to combine multiple graph database instances in a cohesive manner. Thus, Fireplug can support many different deployments, according to the performance/robustness trade-offs imposed by the target application. Our evaluation shows that Fireplug is able implement Byzantine fault tolerance without penalty when compared to the built-in replication mechanism of Neo4j, which only supports crash faults. Additionally, performance optimizations introduced by Fireplug improve the overall performance by up to 900 percent in geo-replicated scenarios.

中文翻译：

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Fireplug：图数据库的高效和健壮的地理复制

尽管图数据库在表现出强烈可靠性要求（包括对恶意故障的容忍度）的应用程序中的相关性越来越大，但很少有工作在这种特定上下文中解决拜占庭容错问题，并且之前的尝试缺乏灵活性和性能不佳。本文描述并评估 Fireplug，这是一种用于构建强大的地理复制图形数据库的灵活架构。Fireplug 可以配置为在不同数据中心内和跨数据中心容忍从崩溃到拜占庭故障。此外，Fireplug 对现有图形数据库实现中的错误具有健壮性，因为它允许以内聚的方式组合多个图形数据库实例。因此，Fireplug 可以支持许多不同的部署，根据目标应用程序强加的性能/健壮性权衡。我们的评估表明，与仅支持崩溃故障的 Neo4j 的内置复制机制相比，Fireplug 能够实现拜占庭容错而不受惩罚。此外，Fireplug 引入的性能优化在异地复制场景中将整体性能提高了 900%。