Performance-Optimal Read-Only Transactions
Performance-Optimal Read-Only Transactions
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发表时间：
2020
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通讯作者：
Haonan Lu;S. Sen;Wyatt Lloyd
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作者：
Haonan Lu;S. Sen;Wyatt Lloyd
只读事务对于一致地读取分布在分布式存储系统上的数据至关重要，但其性能比简单的非事务性读取更差。我们确定了简单读取的三个属性，它们是只读事务实现性能最优所必需的，即尽可能接近简单读取。我们通过证明严格的序列化性（最强的一致性）是不可能实现性能最优的，从而证明了只读事务设计中的一个基本权衡。在此结果的指导下，我们提出了PORT，这是迄今为止具有最强一致性的性能优化设计。PORT的核心是版本时钟，这是一种专门的逻辑时钟，可以简洁地捕获必要的排序约束。我们通过两个应用程序展示PORT的通用性。Scylla-PORT通过简单的写操作提供进程顺序的序列化性，并显示出与其非事务性基础系统相当的性能。eger - port为写事务提供了因果一致性，并显著提高了其事务基础系统的性能。
Read-only transactions are critical for consistently reading data spread across a distributed storage system but have worse performance than simple, non-transactional reads. We identify three properties of simple reads that are necessary for read-only transactions to be performance-optimal, i.e., come as close as possible to simple reads. We demonstrate a fundamental tradeoff in the design of read-only transactions by proving that performance optimality is impossible to achieve with strict serializability, the strongest consistency. Guided by this result, we present PORT, a performance-optimal design with the strongest consistency to date. Central to PORT are version clocks, a specialized logical clock that concisely captures the necessary ordering constraints. We show the generality of PORT with two applications. Scylla-PORT provides process-ordered serializability with simple writes and shows performance comparable to its non-transactional base system. Eiger-PORT provides causal consistency with write transactions and significantly improves the performance of its transactional base system.