基于数据副本读/写轨迹的PRAM一致性研究
Verifying PRAM Consistency over Read/Write Traces of Data Replicas
摘要：
数据复制技术能够实现高效、高可用的数据访问，因此越来越受到学术界和工业界的关注。然而，数据复制引入了数据一致性的问题。现代商业数据复制系统通常在某些故障场景下为高可用性提供弱一致性。一个重要的弱一致性是流水线RAM（PRAM）一致性。它允许不同的进程持有不同的数据视图。为了确定数据复制系统是否确实提供PRAM一致性，我们研究了在读/写跟踪（或简称VPC）上的PRAM一致性问题。我们首先根据a）是否存在多个共享变量（或一个单个变量）以及b）写入操作是否可以为每个共享变量分配重复值（或仅唯一值）来识别VPC的四种变体;这四种变体被标记为VPC-SU，VPC-MU，VPC-SD和VPC-MD。其次，我们提出了一个简单的VPC-MU算法，称为RW-CLOSURE。它根据三条规则迭代添加边来构造操作图$\mathcal{G}$。它的时间复杂度是$O(n^5)$，其中n是跟踪中的操作数。第三，我们提出了一种改进的VPC-MU算法，称为READ-CENTRIC，时间复杂度为$O(n^4)$。基本上，它试图以增量和有效的方式构造操作图$\mathcal{G}$。它的正确性是基于RW-CLOSURE。最后，通过将强$\sf{NP}$ -完全问题3-PARTITION约化为它，证明了VPC-SD（VPC-MD也是）是$\sf{NP}$ -完全的.
英文摘要：
Data replication technologies enable efficient and highly-available data access, thus gaining more and more interests in both the academia and the industry. However, data replication introduces the problem of data consistency. Modern commercial data replication systems often provide weak consistency for high availability under certain failure scenarios. An important weak consistency is Pipelined-RAM (PRAM) consistency. It allows different processes to hold different views of data. To determine whether a data replication system indeed provides PRAM consistency, we study the problem of Verifying PRAM Consistency over read/write traces (or VPC, for short). We first identify four variants of VPC according to a) whether there are Multiple shared variables (or one Single variable), and b) whether write operations can assign Duplicate values (or only Unique values) for each shared variable; the four variants are labeled VPC-SU, VPC-MU, VPC-SD, and VPC-MD. Second, we present a simple VPC-MU algorithm, called RW-CLOSURE. It constructs an operation graph $\mathcal{G}$ by iteratively adding edges according to three rules. Its time complexity is $O(n^5)$, where n is the number of operations in the trace. Third, we present an improved VPC-MU algorithm, called READ-CENTRIC, with time complexity $O(n^4)$. Basically it attempts to construct the operation graph $\mathcal{G}$ in an incremental and efficient way. Its correctness is based on that of RW-CLOSURE. Finally, we prove that VPC-SD (so is VPC-MD) is $\sf{NP}$-complete by reducing the strongly $\sf{NP}$-complete problem 3-PARTITION to it.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
