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- research-articleMay 2023
Proportionality on Spatial Data with Context
ACM Transactions on Database Systems (TODS), Volume 48, Issue 2Article No.: 4, Pages 1–37https://doi.org/10.1145/3588434More often than not, spatial objects are associated with some context, in the form of text, descriptive tags (e.g., points of interest, flickr photos), or linked entities in semantic graphs (e.g., Yago2, DBpedia). Hence, location-based retrieval should be ...
- research-articleDecember 2022
Proximity Queries on Terrain Surface
ACM Transactions on Database Systems (TODS), Volume 47, Issue 4Article No.: 15, Pages 1–59https://doi.org/10.1145/3563773Due to the advance of the geo-spatial positioning and the computer graphics technology, digital terrain data has become increasingly popular nowadays. Query processing on terrain data has attracted considerable attention from both the academic and the ...
- research-articleMay 2022
- research-articleSeptember 2021
Error Bounded Line Simplification Algorithms for Trajectory Compression: An Experimental Evaluation
ACM Transactions on Database Systems (TODS), Volume 46, Issue 3Article No.: 11, Pages 1–44https://doi.org/10.1145/3474373Nowadays, various sensors are collecting, storing, and transmitting tremendous trajectory data, and it is well known that the storage, network bandwidth, and computing resources could be heavily wasted if raw trajectory data is directly adopted. Line ...
- research-articleMarch 2021
Scotty: General and Efficient Open-source Window Aggregation for Stream Processing Systems
- Jonas Traub,
- Philipp Marian Grulich,
- Alejandro Rodríguez Cuéllar,
- Sebastian Breß,
- Asterios Katsifodimos,
- Tilmann Rabl,
- Volker Markl
ACM Transactions on Database Systems (TODS), Volume 46, Issue 1Article No.: 1, Pages 1–46https://doi.org/10.1145/3433675Window aggregation is a core operation in data stream processing. Existing aggregation techniques focus on reducing latency, eliminating redundant computations, or minimizing memory usage. However, each technique operates under different assumptions ...
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- research-articleAugust 2020
Packing R-trees with Space-filling Curves: Theoretical Optimality, Empirical Efficiency, and Bulk-loading Parallelizability
ACM Transactions on Database Systems (TODS), Volume 45, Issue 3Article No.: 14, Pages 1–47https://doi.org/10.1145/3397506The massive amount of data and large variety of data distributions in the big data era call for access methods that are efficient in both query processing and index management, and over both practical and worst-case workloads. To address this need, we ...
- research-articleDecember 2019
General Temporally Biased Sampling Schemes for Online Model Management
ACM Transactions on Database Systems (TODS), Volume 44, Issue 4Article No.: 14, Pages 1–45https://doi.org/10.1145/3360903To maintain the accuracy of supervised learning models in the presence of evolving data streams, we provide temporally biased sampling schemes that weight recent data most heavily, with inclusion probabilities for a given data item decaying over time ...
- surveyMarch 2019
A Survey of Spatial Crowdsourcing
ACM Transactions on Database Systems (TODS), Volume 44, Issue 2Article No.: 8, Pages 1–46https://doi.org/10.1145/3291933Widespread use of advanced mobile devices has led to the emergence of a new class of crowdsourcing called spatial crowdsourcing. Spatial crowdsourcing advances the potential of a crowd to perform tasks related to real-world scenarios involving physical ...
- research-articleMay 2017
COMPRESS: A Comprehensive Framework of Trajectory Compression in Road Networks
ACM Transactions on Database Systems (TODS), Volume 42, Issue 2Article No.: 11, Pages 1–49https://doi.org/10.1145/3015457More and more advanced technologies have become available to collect and integrate an unprecedented amount of data from multiple sources, including GPS trajectories about the traces of moving objects. Given the fact that GPS trajectories are vast in ...
- research-articleOctober 2015
Optimal Location Queries in Road Networks
ACM Transactions on Database Systems (TODS), Volume 40, Issue 3Article No.: 17, Pages 1–41https://doi.org/10.1145/2818179In this article, we study an optimal location query based on a road network. Specifically, given a road network containing clients and servers, an optimal location query finds a location on the road network such that when a new server is set up at this ...
- research-articleJune 2015
Efficient Processing of Spatial Group Keyword Queries
ACM Transactions on Database Systems (TODS), Volume 40, Issue 2Article No.: 13, Pages 1–48https://doi.org/10.1145/2772600With the proliferation of geo-positioning and geo-tagging techniques, spatio-textual objects that possess both a geographical location and a textual description are gaining in prevalence, and spatial keyword queries that exploit both location and ...
- research-articleApril 2013
Moving spatial keyword queries: Formulation, methods, and analysis
ACM Transactions on Database Systems (TODS), Volume 38, Issue 1Article No.: 7, Pages 1–47https://doi.org/10.1145/2445583.2445590Web users and content are increasingly being geo-positioned. This development gives prominence to spatial keyword queries, which involve both the locations and textual descriptions of content. We study the efficient processing of continuously moving top-...
- research-articleDecember 2012
Finding Alternative Shortest Paths in Spatial Networks
ACM Transactions on Database Systems (TODS), Volume 37, Issue 4Article No.: 29, Pages 1–31https://doi.org/10.1145/2389241.2389248Shortest path query is one of the most fundamental queries in spatial network databases. There exist algorithms that can process shortest path queries in real time. However, many complex applications require more than just the calculation of a single ...
- research-articleJune 2012
Cardinal directions between complex regions
ACM Transactions on Database Systems (TODS), Volume 37, Issue 2Article No.: 8, Pages 1–40https://doi.org/10.1145/2188349.2188350Besides topological relationships and approximate relationships, cardinal directions like north and southwest have turned out to be an important class of qualitative spatial relationships. They are of interdisciplinary interest in fields like cognitive ...
- research-articleJune 2011
Reverse data exchange: Coping with nulls
ACM Transactions on Database Systems (TODS), Volume 36, Issue 2Article No.: 11, Pages 1–42https://doi.org/10.1145/1966385.1966389An inverse of a schema mapping M is intended to undo what M does, thus providing a way to perform reverse data exchange. In recent years, three different formalizations of this concept have been introduced and studied, namely the notions of an inverse ...
- research-articleJune 2011
Design and analysis of a ranking approach to private location-based services
ACM Transactions on Database Systems (TODS), Volume 36, Issue 2Article No.: 10, Pages 1–42https://doi.org/10.1145/1966385.1966388Users of mobile services wish to retrieve nearby points of interest without disclosing their locations to the services. This article addresses the challenge of optimizing the query performance while satisfying given location privacy and query accuracy ...
- research-articleJune 2011
Continuous nearest-neighbor search in the presence of obstacles
ACM Transactions on Database Systems (TODS), Volume 36, Issue 2Article No.: 9, Pages 1–43https://doi.org/10.1145/1966385.1966387Despite the ubiquity of physical obstacles (e.g., buildings, hills, and blindages, etc.) in the real world, most of spatial queries ignore the obstacles. In this article, we study a novel form of continuous nearest-neighbor queries in the presence of ...
- research-articleJuly 2010
Privacy-aware location data publishing
ACM Transactions on Database Systems (TODS), Volume 35, Issue 3Article No.: 18, Pages 1–42https://doi.org/10.1145/1806907.1806910This article examines a new problem of k-anonymity with respect to a reference dataset in privacy-aware location data publishing: given a user dataset and a sensitive event dataset, we want to generalize the user dataset such that by joining it with the ...
- research-articleJuly 2010
Continuous online index tuning in moving object databases
ACM Transactions on Database Systems (TODS), Volume 35, Issue 3Article No.: 17, Pages 1–51https://doi.org/10.1145/1806907.1806909In a Moving Object Database (MOD), the dataset, for example, the location of objects and their distribution, and the workload change frequently. Traditional static indexes are not able to cope well with such changes, that is, their effectiveness and ...
- research-articleMay 2010
Optimal matching between spatial datasets under capacity constraints
ACM Transactions on Database Systems (TODS), Volume 35, Issue 2Article No.: 9, Pages 1–44https://doi.org/10.1145/1735886.1735888Consider a set of customers (e.g., WiFi receivers) and a set of service providers (e.g., wireless access points), where each provider has a capacity and the quality of service offered to its customers is anti-proportional to their distance. The Capacity ...