This paper considers algorithms for concurrency control in Distributed database (DDB) systems. Below are the simulating models of the implementation of two-phase locking (2PL) in DDB. From four types 2PL in DDB (Centralized 2PL, Primary copy 2PL, Distributed 2PL and voting 2PL) is viewed Primary copy 2PL, as this protocol is a "transitional" protocol of Centralized 2PL to the Distributed 2PL. T...

One of the most important problems in distributed database systems is the concurrency control. This paper considers algorithms simulating the implementation of centralized two-phase locking (2PL) in distributed database systems and simulation results. It describes specifically the simulations of two-version 2PL and 2PL with integrated timestamp ordering mechanism. In concurrency control method ...

Distributed storage systems run transactions across machines to ensure serializability. Traditional protocols for distributed transactions are based on two-phase locking (2PL) or optimistic concurrency control (OCC). 2PL serializes transactions as soon as they conflict and OCC resorts to aborts, leaving many opportunities for concurrency on the table. This paper presents ROCOCO, a novel concurr...

This paper addresses the problem of transaction management in multidatabase systems where the participating local DBMSs serialize transactions by 2 Phase-Locking (2PL) and synchronize their commit actions through a 2 Phase-Commit protocol (2PC). These DBMSs represent the majority of commercial relational and objectoriented DBMSs. We demonstrate that if local DBMSs support strict 2PL optimizatio...

Two-phase locking (2PL) is the concurrency control mechanism that is used in most commercial database systems. In 2PL, for a transaction to access a data item, it has to hold the appropriate lock (read or write) on the data item by issuing a lock request. While the way transactions set their lock requests and the way the requests are granted would certainly affect a system’s performance, such a...

The increasing demand for high throughputs in transaction processing systems leads to high degrees of transaction concurrency and hence high data contention. The conventional dynamic two-phase locking (2PL) concurrency control (CC) technique causes system thrashing at high data contention levels, restricting transaction throughput. Optimistic concurrency control (OCC) is an alternative strategy...

A real-time system usually requires maintaining a large amount of temporal data objects. These temporal data objects are accessed by application activities (transactions) to generate the ultimate control actions. In many practical applications, realtime systems require not only ensuring transactions finished in the specified time limits (deadlines), but also guaranteeing temporal consistency of...

The DA-T Gibbs sampler is proposed by Maris and Maris (2002) as a Bayesian estimation method for a wide variety of Item Response Theory (IRT) models. The present paper provides an expository account of the DAT Gibbs sampler for the 2PL model. However, the scope is not limited to the 2PL model. It is demonstrated how the DA-T Gibbs sampler for the 2PL may be used to build, quite easily, Gibbs sa...

There is growing evidence that for a wide variety of database workloads and system configurations the two-phase locking (2PL) outperforms other types of concurrency control schemes. However, in the presence of long-lived transactions (LLTs), 2PL surrenders to a problem of long delay suspension because LLTs are qualified to lock data until they commit. To alleviate this problem we propose an ext...

The two-parameter logistic (2PL) item response model is likely the most frequently applied for analyzing dichotomous data. Linking errors quantify variability in means or standard deviations due to choice of items. Previous research presented analytical work linking one-parameter model. In this article, we present 2PL using general theory M-estimation. are derived case log-mean-mean two groups....