Consistency

Title and Author of Paper Consistency Analysis in Bloom: a CALM and Collected Approach. Alvaro et al. Summary Distributed programming is difficult for even experienced developers to get correct. Understanding the tradeoff between consistency, availability, and latency, while guaranteeing data correctness, provides a wealth of problems for the application developer. This paper presents a language and method for programmatically verifying distributed consistency. CALM - Consistency and Logical Monotonicity There is a connection between distributed consistency algorithms and logical monotonicity, that is, our programs must be correct even in the face of the delay and re-ordering of messages and data across different nodes in a system. By designing programs with order independence, we can ensure that the logic of the system is maintained within a distributed environment. ...

Title and Author of Paper Granularity of Locks and Degrees of Consistency in a Shared Data Base. J. Gray et al. Summary This paper is divided in two sections: granularity of locks, and degrees of consistency. Each section answers questions on how lock choice in a database affects throughput and consistency. Granularity of Locks In the granularity section, the choice of lockable units is discussed. A lockable unit represents a section of logical data that is atomically locked during a transaction. Locking smaller units such as individual records improves concurrency for “simple” transactions that access a small number of records. On the other hand, locking at a record level can reduce throughput for “complex” transactions that require access to many records — the overhead of acquiring and releasing locks overwhelms the computation. It follows that having different sizes of lockable units in the same system is required to handle multiple use cases. ...