Due to the escalating demand to analyze large graphs, many organizations are now collecting billion-level property graph datasets, concurrently executing many complex graph queries against them, and expecting interactive-level response latency. However, such requirements are particularly challenging because of the notoriously irregular data access pattern and complex dependencies between heterogeneous subtasks. Despite the widespread availability of many-core CPUs and high-speed networking in modern datacenters, existing distributed graph query systems struggle with their inherent inefficiencies, resulting in low hardware utilization and poor query performance on these state-of-the-art hardware. To address these challenges, we introduce the Partitioned Stateful Traversal Machine (PSTM), which extends the Gremlin graph traversal machine. PSTM retains the expressive power of the Gremlin query language, enabling it to accommodate a wide range of graph query tasks, including traversal, pattern matching, filtering, and result aggregation. It additionally introduces query memoranda, allowing for more efficient implementation and execution of numerous graph queries in distributed environments. Moreover, PSTM facilitates various system-level optimizations, such as massively parallel execution, overlapping computation with communication, locality-aware data access, and lightweight progress tracking. Building upon PSTM, we develop GraphDance, a distributed graph database featuring an efficient asynchronous PSTM run-time. Our evaluations, conducted on an 8-node cluster, show that GraphDance achieves millisecond-level query latency for complex queries on terabyte-scale graphs, with an average latency reduction of 89.2% across all interactive complex queries in the LDBC SNB benchmark compared to existing distributed graph query systems.

Read-only transactions predominate in many critical real-world scenarios. Yet, the presence of even a small proportion of read-write transactions poses challenges for existing Two-Phase Locking (2PL) and Optimistic Concurrency Control (OCC) based disaggregated transaction solutions. These approaches require either atomic operations or double reads to maintain consistent data for serializability, leading to suboptimal performance. This paper introduces OOCC, a novel One-round Optimistic Concurrency Control method tailored for disaggregated trans-actions. We propose that by intentionally postponing updates in write transactions for a moderate duration (a lease), it's possible to skip the validation phase in most OCC cases. This method enables read-only transactions to be completed within a single Round Trip Time (RTT) without involving any atomic operations. Additionally, we introduce several enhancements to boost OOCC's effectiveness in high-contention and write-intensive scenarios by reducing lock durations to just 1 RTT. Our experimental results demonstrate that OOCC significantly boosts transaction throughput in read-heavy environments, showing improvements ranging from 1.2 to 4 times. OOCC consis-tently achieves the lowest average latency (40 % -45 % lower than the best counterpart) in both read- and write-heavy workloads.

Modern stream processing engines (SPEs) must handle massive real-time data streams under strict latency and throughput requirements. However, conventional SPEs are constrained by their software parallelization strategies (e.g., queue-based data re-partitioning, high synchronization overheads, etc.), which prevent efficient utilization of modern hardware capabilities, ultimately limiting performance scalability. In this paper, we present FlexStream, a novel SPE that leverages hardware offloading to redesign the parallelization strategies and overcome these limitations. By offloading data re-partitioning to hardware and integrating a coupled network-executor model, FlexStream maximizes resource utilization, achieving up to 95% network bandwidth saturation. To address the load imbalance challenges introduced by this design, we implement a lock-free state backend with efficient state migration mechanisms. Overall, FlexStream achieves throughput improvements of 1.95 × - 3.35 × compared to state-of-the-art SPEs (e.g., LightSaber) across six real-world streaming analytics applications. FlexStream cuts latency spikes by 71.9% and migration time by 66.8% during state migration, highlighting the benefits of hardware-software co-design in SPEs. Our work underscores the potential of hardware-software co-design in SPEs, offering a scalable, elastic solution for real-time analytics.

Graph databases play a pivotal role in the FinTech industry. However, existing graph benchmarks fail to capture the unique characteristics of financial datasets and workloads, rendering them inadequate for evaluating graph databases in financial scenarios. This paper presents the LDBC Financial Benchmark (FinBench) Transaction Workload, a novel benchmark that adopts a choke point-driven design methodology, emphasizing performance bottlenecks, and incorporates distinct features such as dataset skewness, edge multiplicity, temporal window filtering, recursive path filtering, read-write query patterns, and truncation on hub vertices. Key contributions include a scalable data generator that synthesizes datasets with financial-specific features, a parameter generator that leverages bucketed data statistics for runtime consistency across queries, and a scalable benchmark driver that biases query execution by time windows. Experimental evaluations on graph databases demonstrate the benchmark's capability to reveal novel choke points and provide insights into system performance in financial scenarios.

Temporal graphs attach time information to edges and are commonly used for implementing time-critical applications that can not be effectively processed by traditional static and dynamic graph processing engines. State-of-the-art solutions that target temporal path problems remain ad-hoc and often suboptimal. A unified and high-performance solution that could efficiently process general temporal path problems via a universal optimization strategy and relieve practitioners from heavy optimization efforts is in urgent demand. In this paper, we make two key observations: (1) temporal path problems can be described as topological-optimum problems and solved by a universal single scan execution model; and (2) data redundancy commonly occurs in the native format of the transformed temporal graphs, which is unnecessary for information propagation and can be eliminated for better memory utilization and execution efficiency. Based on these core insights, we propose TegRaph, the first general-purpose temporal graph computing engine to provide a unified optimization strategy and execution model for general temporal path problems and their applications. TegRaph not only presents temporal information-aware graph representation that naturally fits temporal graphs but also offers general system-level supports such as out-of-core execution. Extensive evaluation reveals that TegRaph can achieve significant speedups over the state-of-the-art designs with up to two orders of magnitude (241×) with the throughput of two hundred million edges per second.

With the rapid development of mobile Internet technology, Internet users are shifting from desktop to mobile devices. Modern mobile devices (e.g., smartphones and tablets) are equipped with GPS, which can help users to easily obtain their locations, and location-based services (LBS) have been widely deployed. LBS users are generating more and more spatio-textual data which contains both textual descriptions and geographical locations. In user-generated data, a spatiotextual entity may have different representations, possibly due to GPS deviations or typographical errors [6], [2], and it calls for effective methods to integrate the spatio-textual data from different data sources. A spatio-textual similarity join is an important operation in spatio-textual data integration, which, given two sets of spatio-textual objects, finds all similar pairs from the two sets, where the similarity can be quantified by combining spatial proximity and textual relevancy. There are many applications in spatio-textual similarity joins, e.g., user recommendation in location-based social networks, image duplication detection using spatio-textual tags, spatio-textual advertising, and location-based market analysis [6], [2]. For example, a house rental agency (e.g., rent.com) wants to perform a similarity join on the spatio-textual data of house requirements from renters and the data of house properties from owners. For another example, a startup company, e.g., Factual (factual.com), crawls spatio-textual records to generate points of interest (POIs). As the records are from multiple sources and may contain many duplicates, It needs to run similarity joins to remove the duplicates.

Nowadays, there is a rising trend of building array-based distributed computing frameworks, which are suitable for implementing many machine learning and data mining algorithms. However, most of these frameworks only execute each primitive in an isolated manner and in the exact order defined by programmers, which implies a huge space for optimization. In this paper, we propose a novel array-based programming model, named K asen , which distinguishes itself from models in the existing literature by defining a strict computation and communication model. This model makes it easy to analyze programs' behavior and measure their performance, with which we design a corresponding optimizer that can automatically apply high-level optimizations to the original programs written by programmers. According to our evaluation, the optimizer of K asen can achieve a significant reduction on memory read/write, buffer allocation and network traffic, which leads to a speedup up to 5.82x.

With the development of location-based services (LBS), LBS users are generating more and more spatio-textual data, e.g., checkins and attraction reviews. Since a spatio-textual entity may have different representations, possibly due to GPS deviations or typographical errors, it calls for effective methods to integrate the spatio-textual data from different data sources. In this paper, we study the problem of top-$k$spatio-textual similarity join (Topk-STJoin), which identifies the$k$most similar pairs from two spatio-textual data sets. One big challenge inTopk-STJoinis to efficiently identify the top-$k$similar pairs by considering both textual relevancy and spatial proximity. Traditional join algorithms that consider only one dimension (textual or spatial) are inefficient because they cannot utilize the pruning ability on the other dimension. To address this challenge, we propose a signature-based top-$k$join framework. We first generate a spatio-textual signature set for each object such that if two objects are in the top-$k$similar pairs, their signature sets must overlap. With this property, we can prune large numbers of dissimilar pairs without common signatures. We find that the order of accessing the signatures has a significant effect on the performance. So, we compute an upper bound for each signature and propose a best-first accessing method that preferentially accesses signatures with large upper bounds while those pairs with small upper bounds can be pruned. We prove the optimality of our best-first accessing method. Next, we optimize the spatio-textual signatures and propose progressive signatures to further improve the pruning power. Experimental results on real-world datasets show that our algorithm achieves high performance and good scalability, and significantly outperforms baseline approaches.