Reverse$k$nearest neighbor search$(\mathbf{R}k\mathbf{NNS})$plays an important role in various data processing and analysis tasks, seeking to pinpoint data considering the query data$q$among their$k$nearest neighbors. As large models gain popularity, processing high-dimensional vectors has become more and more widespread. However, existing$\mathbf{R}k\mathbf{NNS}$solutions face inefficiency when handling large-scale high-dimensional vectors due to their sensitivity to data dimensions and sizes during index construction or the verification of numerous candidate results in the query phase. Motivated by these challenges and the inherent intricacies of high-dimensional data processing, in this paper, we study an approximate version of the$\mathbf{R}k\mathbf{NNS}$problem$(\mathbf{R}k\mathbf{ANNS})$for high-dimensional vectors, aiming to offer efficient and practical solutions. To this end, we propose a new proximity-graph-based index called HAMG, which enables finding the query results within$k$hops from$q$. We also present a user-friendly query algorithm on HAMG that can adaptively adjust the search scope based on the desired query recall of users. To further enhance the query process, two pruning strategies are proposed to reduce the number of candidates requiring verification. Extensive experiments validate that HAMG scales well for data dimensions and sizes, and our query algorithm improves query efficiency by up to two orders of magnitude while maintaining comparable query accuracy against existing approaches.

The development of Earth Observation technology contributes to the production of massive raster data. It is vital to manage and conduct analytical tasks on the raster data. Existing solutions employ dedicated systems for the raster data management and processing, respectively, incurring problems such as data redundancy, difficulty in updating, expensive data transferring and transformation, etc. To cope with these limitations, this demonstration presents Ganos Aero, a cloud-native system for big raster data management and processing. Ganos Aero proposes a unified raster data model for both the data management and processing, which stores a single copy of the raster data and without performing an expensive tiling procedure, and thus achieves significant improvement in the storage and updating efficiency. To enable efficient query and batch task processing, Ganos Aero implements an on-the-fly tile production mechanism, and optimizes its performance using the cloud features including decoupling compute from storage and pushing costly operations closer to the storage layer. Since deployed in Alibaba Cloud in 2022, Ganos Aero has been playing a critical role in many real applications including the modern agriculture, environment monitoring and protection, et al.

Recently, the trend of developing digital twins for smart cities has driven a need for managing large-scale multidimensional, dynamic, and scene-oriented spatial data. Due to larger data scale and more complex data structure, queries over such data are more complicated and expensive than those on traditional spatial data, which poses challenges to the system efficiency and deployment costs. The existing spatial databases have limited support in both data types and operations. Therefore, a new-generation spatial database with excellent performance and effective deployment costs is needed. This paper presents Ganos, a cloud-native spatial database engine of PolarDB for PostgreSQL that is developed by Alibaba Cloud, to efficiently manage multidimensional, dynamic, and scene-oriented spatial data. Ganos models 3D space and spatio-temporal dynamics as first-class citizens. Also, it natively supports spatial/spatio-temporal data types such as 3DMesh, Trajectory, Raster, PointCloud, etc. Besides, it implements a novel extended-storage mechanism that utilizes cloud-native object storage to reduce storage costs and enable uniform operations on the data in different storages. To facilitate processing "big" queries, Ganos extends PolarDB and provides spatial-oriented multi-level parallelism under the architecture of decoupling compute from storage in cloud-native databases, which achieves elasticity and excellent query performance. We demonstrate Ganos in real-life case studies. The performance of Ganos is evaluated using real datasets, and promising results are obtained. Finally, based on the extensive deployment and application of Ganos, the lessons learned from our customers and the expectations of modern cloud applications for new spatial database features are discussed.

The proliferation of mobile phones and location-based services has given rise to an explosive growth in spatial data. In order to enable spatial data analytics, spatial data needs to be streamed into a data stream warehouse system that can provide real-time analytical results over the most recent and historical spatial data in the warehouse. Existing data stream warehouse systems are not tailored for spatial data. In this paper, we introduce the STAR (Spatial Data Stream Warehouse) system. STAR is a distributed in-memory data stream warehouse system that provides low-latency and up-to-date analytical results over a fast-arriving spatial data stream. STAR supports queries that are composed of aggregate functions and ad hoc query constraints over spatial, textual, and temporal data attributes. STAR implements a cache-based mechanism to facilitate the processing of queries that collectively utilizes the techniques of query-based caching (i.e., view materialization) and object-based caching. Extensive experiments over real data sets demonstrate the superior performance of STAR over existing systems.

The proliferation of mobile phones and location-based services gives rise to an explosive growth of spatial data. This spatial data contains valuable information, and calls for data stream warehouse systems that can provide real-time analytical results with the latest integrated spatial data. In this demonstration, we present the STAR (Spatial Data Stream Warehouse) system. STAR is a distributed in-memory spatial data stream warehouse system that provides low-latency and up-to-date analytical results over a fast spatial data stream. STAR supports a rich set of aggregate queries for spatial data analytics, e.g., contrasting the frequencies of spatial objects that appear in different spatial regions, or showing the most frequently mentioned topics being tweeted in different cities. STAR processes aggregate queries by maintaining distributed materialized views. Additionally, STAR supports dynamic load adjustment that makes STAR scalable and adaptive. We demonstrate STAR on top of Amazon EC2 clusters using real data sets.

Huge amount of data with both space and text information, e.g., geo-tagged tweets, is flooding on the Internet. Such spatio-textual data stream contains valuable information for millions of users with various interests on different keywords and locations. Publish/subscribe systems enable efficient and effective information distribution by allowing users to register continuous queries with both spatial and textual constraints. However, the explosive growth of data scale and user base has posed challenges to the existing centralized publish/subscribe systems for spatiotextual data streams. In this paper, we propose our distributed publish/subscribe system, called PS2Stream, which digests a massive spatio-textual data stream and directs the stream to target users with registered interests. Compared with existing systems, PS2Stream achieves a better workload distribution in terms of both minimizing the total amount of workload and balancing the load of workers. To achieve this, we propose a new workload distribution algorithm considering both space and text properties of the data. Additionally, PS2Stream supports dynamic load adjustments to adapt to the change of the workload, which makes PS2Stream adaptive. Extensive empirical evaluation, on commercial cloud computing platform with real data, validates the superiority of our system design and advantages of our techniques on system performance improvement.

Rich geo-textual data is available online and the data keeps increasing at a high speed. We propose two user behavior models to learn several types of user preferences from geo-textual data, and a prototype system on top of the user pre ference models for min ing and s e a r ch geo-textual data (called PreMiner) to support personalized maps. Different from existing recommender systems and data analysis systems, PreMiner highly personalizes user experience on maps and supports several applications, including user mobility & interests mining, opinion mining in regions, user recommendation, point-of-interest recommendation, and querying and subscribing on geo-textual data.