Safe Locking Policies for Dynamic Databases

AbstractYannakakis showed that a locking policy is not safe if and only if it allows a canonical nonserializable schedule of transactions in which all transactions except one are executed serially (Yannakakis, 1982). In the present paper, we study the generalization of this result to a dynamic database, that is, a database that may undergo insertions and deletions of entities. We illustrate the utility of this generalization by applying it to obtain correctness proofs of three locking policies that handle dynamic databases

A Concurrency-Optimal Binary Search Tree

The paper presents the first \emph{concurrency-optimal} implementation of a binary search tree (BST). The implementation, based on a standard sequential implementation of an internal tree, ensures that every \emph{schedule} is accepted, i.e., interleaving of steps of the sequential code, unless linearizability is violated. To ensure this property, we use a novel read-write locking scheme that protects tree \emph{edges} in addition to nodes. Our implementation outperforms the state-of-the art BSTs on most basic workloads, which suggests that optimizing the set of accepted schedules of the sequential code can be an adequate design principle for efficient concurrent data structures

Safe Locking Policies for Dynamic Databases

It was shown by Yannakakis that a locking policy is not safe if and only if there exists a canonical non-serializable schedule of transactions running according to the rules of the policy in which all the transactions except one are executed serially [Yan82]. In the present paper, we study the generalization of this result to a dynamic database, that is, a database that may undergo insertions and deletions of entities. We illustrate the utility of this generalization by applying it to obtain correctness proofs of three locking policies that handle dynamic databases. Keywords: Concurrency Control, Correctness Issues Safe Locking Policies for Dynamic Databases 1 1 Introduction A locking policy is called safe if any concurrent execution of a set of transactions while locked according to that policy is guaranteed to be correct. Yannakakis showed that a locking policy is not safe if and only if there exists a canonical non-serializable schedule in which all transactions except one ..