Transaction support for indexed summary views

In the intricate world of financial data replication, conflicts are inevitable, especially in distributed environments where data is constantly moving across multiple systems. This article delves into the various strategies employed to tackle these conflicts, ensuring data integrity and consistency. We begin by exploring the common sources of conflict in financial data replication, such as network latency, system failures, and concurrent updates. Recognizing these challenges, we discuss the importance of establishing robust conflict resolution mechanisms. The article highlights several key strategies, including timestamp-based conflict resolution, where the most recent update prevails, and versioning, which maintains multiple versions of data to handle discrepancies. We also examine the use of consensus algorithms, such as Paxos and Raft, to achieve agreement among distributed nodes. These techniques are essential for maintaining the accuracy and reliability of financial data, which is crucial for decision-making and compliance. Additionally, we look at real-world examples and case studies that illustrate the successful implementation of these strategies in financial institutions. By understanding the practical applications, readers can better appreciate the complexities and solutions involved in financial data replication. Ultimately, this article aims to provide a comprehensive overview of conflict resolution strategies, offering valuable insights for professionals involved in managing financial data systems. By adopting these strategies, organizations can enhance their data replication processes, ensuring seamless operations and fostering trust in their financial systems.

Consistency guarantees among concurrently executing transactions in local- and distributed systems, commonly referred to as isolation levels, have been formalized in a number of models. Thus far, no model can reason about executable implementations of databases or local transaction libraries providing weak isolation levels. Weak isolation levels are characterized by being highly concurrent and, unlike their stronger counterpart serializability, they are not equivalent to the consistency guarantees provided by a transaction library implemented using a global lock. Industrial-strength databases almost exclusively implement weak isolation levels as their default level. This calls for formalism as numerous bugs violating isolation have been detected in these databases. In this paper, we formalize three weak isolation levels in separation logic, namely read uncommitted , read committed , and snapshot isolation . We define modular separation logic specifications that are independent of the underlying transaction library implementation. Historically, isolation levels have been specified using examples of executions between concurrent transactions that are not allowed to occur, and we demonstrate that our specifications correctly prohibit such examples. To show that our specifications are realizable, we formally verify that an executable implementation of a key-value database running the multi-version concurrency control algorithm from the original snapshot isolation paper satisfies our specification of snapshot isolation. Moreover, we prove implications between the specifications—snapshot isolation implies read committed and read committed implies read uncommitted—and thus the verification effort of the database serves as proof that all of our specifications are realizable. All results are mechanized in the Rocq proof assistant on top of the Iris separation logic framework.

ВычИсленИе среДнего ВременИ «жИзнИ» оДного Класса резерВИроВанных ВосстанаВлИВаемых После отКазоВ сИстем ПрИ ПроИзВольной Во ВременИ ИнтенсИВностИ отКазоВ И ВосстаноВленИяДля резервированной восстанавливаемой после отказов системы, состоящей из n идентичных основных и одного резервного блока при произвольной во времени интенсивности отказов и восстановления найден класс функций интенсивностей восстановления, обеспечивающих в среднем, при заданной функции интенсивности отказов блоков, работоспособное состояние рассматриваемой системы в течение заданного времени

The increasingly large ensemble size of modern High-Performance Computing (HPC) systems has drastically increased the possibility of failures. Performance under failures and its optimization become timely important issues facing the HPC community. In this study, we propose an analytical model to predict the application performance. The model characterizes the impact of coordinated checkpointing and system failures on application performance, considering all the factors including workload, the number of nodes, failure arrival rate, recovery cost, and checkpointing interval and overhead. Based on the model, we gauge three parameters, the number of compute nodes, checkpointing interval, and the number of spare nodes to conduct a comprehensive study of performance optimization under failures. Performance scalability under failures is also studied to explore the performance improvement space for different parameters. Experimental results from both synthetic and actual system failure logs confirm that the proposed model and optimization methodologies are effective and feasible.

We address, the issue of reading the entire database by the broadcast transaction for data broadcasting in mobile environments. The broadcast transaction is a long-lived read-only transaction which creates significant amount of data conflicts with other concurrent update transactions. Using conventional concurrency control to handle the broadcast transaction is inadequate. Recently, some algorithms are proposed for reading the entire database. However, they suffer from late detection of data conflicts. This leads to many data entities being locked unnecessarily, reducing the availability of data. To solve this problem, an effective protocol based on a data locking approach is devised. Data conflicts can be detected at the early stage of the execution of update transactions by a set of predefined rules. As a result, the lock holding time of data entities is effectively reduced and unnecessary acquisitions of data locks are avoided. The simulation results show that the system performance can be significantly improved.

Heterogeneous real-time spatial data management is a very active research domain nowadays. We are talking about a real-time spatial big data that process a large amount of heterogeneous data accessed simultaneously by two types of transactions update transactions and user transactions. In these applications, it is desirable to execute transactions within their deadlines using a real-time spatial data. But the real-time spatial big data can be overloaded and many transactions may miss their deadlines, or real-time spatial data can be violated. To address these problems, we proposed, as a first contribution, a new architecture called feedback control scheduling architecture for real-time spatial big data (FCSA-RTSBD) (Hamdi et al., 2015). Then, we propose, as a second contribution, two-shadow speculative concurrency control (SCC-2S) with priority and imprecise computation (SCC-2S-P-IC). Finally, a simulation study is shown to prove that our contributions can achieve a significant performance improvement using the TPC-DS (TPC, 2014) benchmark.

Butyrylcholinesterase (BChE) can modulate the expression level of cholinesterase, which emerges as an important clinical diagnose index. However, the currently reported assays for BChE are suffering from the problem of interferences. A ratiometric fluorescence assay was developed based on the MnO2 nanosheet (NS)-modulated fluorescence of sulfur quantum dots (S-dots) and o-phenylenediamine (OPD). MnO2 NS can not only quench the fluorescence of blue emissive S-dots, but also enhance the yellow emissive OPD by catalyzing its oxidation reactions. Upon introducing BChE and substrate into the system, their hydrolysate can reduce MnO2 into Mn2+, leading to the fluorescence recovery of S-dots and failure of OPD oxidation. BChE activity can be quantitatively detected by recording the change of fluorescence signals in the blue and yellow regions. A linear relationship is observed between the ratio of F435/F560 and the concentration of BChE in the range 30 to 500U/L, and a limit of detection of 17.8U/L has been calculated. The ratiometric fluorescence assay shows an excellent selectivity to acetylcholinesterase and tolerance to variousother species. The method developed provides good detection performances in human serum medium and for screening of inhibitors.

Performance in database systems is strongly influenced by buffer management and transaction recovery methods. This paper presents the principles of the database cache, which replaces the traditional buffer. In comparison to buffer management, cache management is more carefully coordinated with transaction management, and integrates transaction recovery. High throughput of small- and medium-sized transactions is achieved by fast commit processing and low database traffic. Very fast handling of transaction failures and short restart time after system failure are guaranteed in such an environment. Very long retrieval and update transactions are also supported.

It has not been well established whether the oxidative stress found in cancer patients results from an increased production of oxidants in the body or from a failure of physiological antioxidant systems. To further investigate this question, we have assessed the blood levels of reactive oxygen species as a marker of free radicals producing oxidative stress and the most relevant of the physiological body enzymes counteracting reactive oxygen species, namely glutathione peroxidase and superoxide dismutase. We also investigated serum levels of proinflammatory cytokines and IL-2. All of these parameters were studied in relation to the most important clinical index of disease progression--namely, the Eastern Cooperative Oncology Group (ECOG) Performance Status (PS). We also tested the reducing ability of different antioxidant agents on reactive oxygen species levels by measuring the increase in glutathione peroxidase activity and the reduction of serum levels of IL-6 and TNF-alpha. We carried out an open nonrandomized study on 28 advanced stage cancer patients (stage III, 10.7% and stage IV, 89.3%) with tumors at different sites. The patients were divided into 5 groups, and a different antioxidant treatment was administered to each group. The antioxidants were alpha lipoic acid 200 mg/day orally; N-acetylcysteine 1800 mg/day i.v. or carboxycysteine-lysine salt 2.7 g/day orally; amifostine 375 mg/day i.v.; reduced glutathione 600 mg/day i.v.; and a combination of vitamin A 30,000 IU/day orally, vitamin E 70 mg/day orally, and vitamin C 500 mg/day orally. The antioxidant treatment was administered for 10 consecutive days. We found that all but one of the antioxidants tested were effective in reducing reactive oxygen species levels, and two of them (cysteine-containing compounds and amifostine) had the additional effect of increasing glutathione peroxidase activity. Comprehensively, the antioxidant treatment was found to have an effect on both reactive oxygen species levels and glutathione peroxidase activity. The antioxidant treatment also reduced the serum levels of IL-6 and TNF-alpha. Patients in both ECOG PS 0-1 and ECOG PS 2-3 responded to antioxidant treatment.

Modern web services crucially rely on high-performance distributed databases, where concurrent transactions are isolated from each other using concurrency control protocols. Relaxed isolation levels, which permit more complex concurrent behaviors than strong levels like serializability, are used in practice for higher performance and availability. In this paper, we present Eiger-PORT+, a concurrency control protocol that achieves a strong form of causal consistency, called TCCv (Transactional Causal Consistency with convergence). We show that Eiger-PORT+ also provides performance-optimal read transactions in the presence of transactional writes, thus refuting an open conjecture that this is impossible for TCCv. We also deductively verify that Eiger-PORT+ satisfies this isolation level by refining an abstract model of transactions. This yields the first deductive verification of a complex concurrency control protocol. Furthermore, we conduct a performance evaluation showing Eiger-PORT+ ’s superior performance over the state-of-the-art.

The authors propose a method for using redundant disk arrays to support rapid recovery from system crashes and transaction aborts in addition to their role in providing media failure recovery. A twin-page scheme is used to store the parity information in the array, making it possible to keep the old version of the parity along with the new version. The old version of the parity is used to undo updates performed by aborted transactions or by transactions interrupted by a system failure. Using an analytical model, it is shown that the proposed method achieves a significant increase in the throughput of database systems using redundant disk arrays by reducing the number of recovery operations needed to maintain the consistency of the database. >

The failure of urban Electrical Distribution Systems (EDSs) can lead to direct or indirect consequences for their interdependent critical infrastructures, for example, the hospitals, the fire department, etc., negatively affecting the well-being of citizens in the city. To improve the resilience of the coupled power network, the Operational Interdependence Simulator (OIS) is proposed to help prioritize the queue of failure recovery and Minimum Spanning Tree and Shortest Path Tree topology reconfiguration to minimize critical load downtime. Additionally, AI agents are introduced to assist decision-making processes. By utilizing machine learning and training in thousands of offline scenarios, the system can be used for real-time calculation of the optimal recovery paths when given the number and location of electrical faults. The IEEE 70-node distribution system case validated the high prediction accuracy and post-disaster topology reconfiguration while considering the interdependencies.

A single base repeater failure in TDMA wireless systems causes all active calls on this base repeater to be dropped. In order to increase the system end-to-end availability, an RF channel recovery method for TDMA wireless systems is proposed in this paper. By applying the method, when a base repeater fails, the channels of active calls carried by the base repeater are replaced by working channels in the channel pool of the base site. All the active calls continue without the intervention of end users. The method deals not only with the failure and recovery of base repeaters, but also with the channel failure recovery in handoff processes, transient channel failures, and new call setup processes. To predict system availability and performance, hierarchical stochastic reward net (SRN) models are developed for analyzing channel allocation, base repeater failure/repair, and channel recovery. The results show that the recovery method can nearly eliminate dropped calls when the traffic load is light, and can dramatically reduce dropped calls when the traffic load is normal. The price we pay is a slightly increased blocking probability, nearly transparent to the end users.

This paper presents an analytical approach for a k-out-of-n system with units having the failure detection, isolation, and recovery mechanisms. The approach uses the flow-graph concept and moment generating function (MGF) to analyze the reliability of the k-out-of-n system with self-loop units. This newly developed analytical approach provides the probability of system failure, system mean, and standard deviation time to failure. A solved example is presented to demonstrate the application of the approach.

Implementation of information technology (IT) in healthcare has increased with little attention paid to the consequences of system failures. This qualitative study assesses the organizational understanding of IT vulnerabilities, the potential consequences of failure and system recovery capabilities within a large healthcare facility. Fifty nine percent (59%) of identified software applications were rated mission critical by participants, 46% were medium impact and 1 application was a non-factor. Downtime procedures were in place for only 39% of applications with 30% of those deemed “mission-critical” lacking downtime procedures. Expected recovery time objectives (RTO) and recovery point objectives (RPO) for users were not consistent with those projected by the IT department. A sub-analysis of the emergency department showed a high percentage of mission critical software but only 36% had downtime procedures. Continued inattention to the risks and hazards associated with widely disseminated IT within healthcare represents a continuing and little discussed vulnerability.