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Contribution Details
| Type | Conference or Workshop Paper |
| Scope | Discipline-based scholarship |
| Published in Proceedings | Yes |
| Title | Sequenced spatio-temporal aggregation in road networks |
| Organization Unit | |
| Authors |
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| Presentation Type | paper |
| Item Subtype | Original Work |
| Refereed | Yes |
| Status | Published in final form |
| Language |
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| Page Range | 48 - 59 |
| Event Title | EDBT '09: Proceedings of the 12th International Conference on Extending Database Technology |
| Event Type | conference |
| Event Location | St. Petersburg, Russia |
| Event Start Date | March 24 - 2009 |
| Event End Date | March 26 - 2009 |
| Place of Publication | New York, USA |
| Publisher | ACM |
| Abstract Text | Many applications of spatio-temporal databases require support for sequenced spatio-temporal (SST) aggregation, e. g., when analyzing traffic density in a city. Conceptually, an SST aggregation produces one aggregate value for each point in time and space.This paper is the first to propose a method to efficiently evaluate SST aggregation queries for the COUNT, SUM, and AVG aggregation functions. Based on a discrete time model and a discrete, 1.5 dimensional space model that represents a road network, we generalize the concept of (temporal) constant intervals towards constant rectangles that represent maximal rectangles in the space-time domain over which the aggregation result is constant. We propose a new data structure, termed SST-tree, which extends the Balanced Tree for one-dimensional temporal aggregation towards the support for two-dimensional, spatio-temporal aggregation. The main feature of the Balanced Tree to store constant intervals in a compact way by using two counters is extended towards a compact representation of constant rectangles in the space-time domain. We propose and evaluate two variants of the SST-tree. The SSTT-tree and SSTH-tree use trees and hashmaps to manage spacestamps, respectively. Our experiments show that both solutions outperform a brute force approach in terms of memory and time. The SSTH-tree is more efficient in terms of memory, whereas the SSTT-tree is more efficient in terms of time. |
| Digital Object Identifier | 10.1145/1516360.1516368 |
| Other Identification Number | merlin-id:2294 |
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