In database management systems, concurrency control manages the interleaved execution of multiple transactions, ensuring data integrity and consistency. However, in high-conflict scenarios, current strategies often lead to frequent transaction aborts, resulting in a significant waste of time on ineffective operations. To effectively address this challenge, we introduce an innovative Prior Cascading Concurrency Control (PC3) mechanism. This mechanism aims to proactively predict conflicts and minimize the performance penalty caused by these conflicts through a series of precise decisions. Specifically, PC3employs various prediction models to forecast transaction working sets, providing accurate transaction information for conflict detection. On this basis, we implemented a hash-based conflict detection method and established a cascading decision algorithm to minimize transaction abort frequency. Experimental results on the TPC-C workload show that in high-conflict scenarios with a Zipfian skew and thread counts between 5 and 40, PC3reduces the number of erroneous transactions by 18 times, and increases throughput by approximately 30.7%. compared to the best-performing optimistic methods.

In recent times, model-driven deep learning has evolved an iterative algorithm into a cascade network by replacing the regularizer's first-order information, such as the (sub)gradient or proximal operator, with a network module. This approach offers greater explainability and predictability compared to typical data-driven networks. However, in theory, there is no assurance that a functional regularizer exists whose first-order information matches the substituted network module. This implies that the unrolled network output may not align with the regularization models. Furthermore, there are few established theories that guarantee global convergence and robustness (regularity) of unrolled networks under practical assumptions. To address this gap, we propose a safeguarded methodology for network unrolling. Specifically, for parallel MR imaging, we unroll a zeroth-order algorithm, where the network module serves as a regularizer itself, allowing the network output to be covered by a regularization model. Additionally, inspired by deep equilibrium models, we conduct the unrolled network before backpropagation to converge to a fixed point and then demonstrate that it can tightly approximate the actual MR image. We also prove that the proposed network is robust against noisy interferences if the measurement data contain noise. Finally, numerical experiments indicate that the proposed network consistently outperforms state-of-the-art MRI reconstruction methods, including traditional regularization and unrolled deep learning techniques.

Given an sql, a rdbms performs a series of operations to generate a Query Execution Plan (qep), which tells how the results will be collected and returned eventually. The whole pipeline for obtaining the qep is the core functionality of a rdbms, thus is definitely a fundamental knowledge that must be acquired by database learners and junior engineers of any rdbms. Unfortunately, though the majority of rdbmss provide EXPLAIN statement to show the qep, general users cannot see how/why these plans are generated. The only way for learning that is to turn to the textbook, which contains limited number of predefined examples accordingly. However, they are too sketchy to allow us to have a hand-on experience in practice. In this work, we present a general framework, DBinsight, that unveils the query processing pipeline visually at each phase during the processing pipeline, including parsing, translating, query optimization, etc. Considering that the underlying designs and optimization strategies of rdbmss are different, in DBinsight we present an SQPProfile interface, such that heterogeneous data structures in various rdbmss are normalized to a uniform format. Thanks to that, in DBinsight we only need to focus on offering the presentation and interaction functionalities based on the uniformed SQPProfile, and do not need to worry about the difference in the underlying rdbmss.

Context plays an important role in helping users to make decisions. There are hierarchical structure between contexts and aggregation characteristics within the context in real scenarios. Exist works mainly focus on exploring the explicit hierarchy between contexts, while ignoring the aggregation characteristics within the context. In this work, we explore both of them so as to improve accuracy of prediction in recommender systems. We propose a Random Partition Factorization Machines (RPFM) by adopting random decision trees to split the contexts hierarchically to better capture the local complex interplay. The intuition here is that local homogeneous contexts tend to generate similar ratings. During prediction, our method goes through from the root to the leaves and borrows from predictions at higher level when there is sparseness at lower level. Other than estimation accuracy of ratings, RPFM also reduces the over-fitting by building an ensemble model on multiple decision trees. We test RPFM over three different benchmark contextual datasets. Experimental results demonstrate that RPFM outperforms state-of-the-art context-aware recommendation methods.

It is popular for most people to read news online since the web sites can provide access to news articles from millions of sources around the world. For these news web sites, the key challenge is to help users find related news articles to read. In this paper, we present a system called CROWN (Context-aware RecOmmender for Web News) to do Chinese news recommendation. By recommendation, the system can retrieve personalized fresh and relevant news articles to mobile users according to their particular context. Differing from existing mobile news applications which employ rather simple strategies for news recommendation, CROWN integrates the contextual information in prediction by modeling the data as a tensor. Such context information usually includes the time, the location, etc. This demo paper presents the implementation of the whole procedure of news recommendation in the system of CROWN. Experimental results on a large corpus of newly-published Chinese web news show its performance is satisfactory.