Query Processing in Structured Peer-to-Peer Networks

最近，提供分布式哈希表(DHT)功能的新一代P2P系统被提出。这些系统大大提高了P2P系统的可扩展性和精确匹配的准确率，但只提供了精确匹配的查询功能。该提案概述了在基于分布式哈希表的P2P系统上建立复杂查询设施的研究议程。提出的研究议程有三个定义方向：核心代数：探索在P2P网络中运行分布式哈希表的一组核心代数查询操作符的实现。分布式哈希表API：确定P2P网络需要实现的最小原语和功能集，以便有效地支持查询操作符。查询优化：P2P网络通常分布在速度较慢的网络链接上，可能会从使用半联接等分布式数据库优化中受益。然而，目前还不清楚查询处理文献中的各种想法如何映射到P2P上下文中，特别是在查询处理期间使用DHTs进行路由时。该方案旨在研究查询计划空间的各种方案的代价和权衡，并将使用大型网络的模拟来研究所提出的因特网规模的技术。

Recently a new generation of P2P systems, offering distributed hashtable (DHT) functionality, have been proposed. These systems greatlyimprove the scalability and exact-match accuracy of P2P systems, butoffer only the exact-match query facility. This proposal outlines aresearch agenda for building complex query facilities on top of theseDHT-based P2P systems. There are three defining directions of theproposed research agenda: Core Algebra: Explore the implementation of a core set of algebraic query operators that run over DHTs in a P2P network. DHT APIs: Identify the minimum set of primitives and functions that need to be implemented by a P2P network in order to efficiently support the query operators. Query Optimization: P2P networks are often distributed across slow network links, and may benefit from distributed database optimizations like the use of semi-joins. However, it is not clear how the various ideas in the query processing literature map into the P2P context, particularly when using DHTs for routing during query processing. This proposal intends to study the costs and tradeoffs of various alternatives for the query plan space in this context.Simulation of large networks will be used to study the proposedtechniques at Internet scale.