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| creator |
Lange, Ralph
| | Dürr, Frank
| | Rothermel, Kurt
| | date |
2008-11-05
| | | | description |
Space-partitioned Moving Objects Databases (SP-MODs) allow for the
scalable, distributed management of large sets of mobile
objects' trajectories by partitioning the trajectory data to a
network of database servers. Processing a spatio-temporal query q
therefore requires efficiently routing q to the servers storing the
affected trajectory segments. With a coordinate-based query - like a
spatio-temporal range query - the relevant servers are directly
determined by the queried range. However, with trajectory-based
queries - like retrieving the distance covered by a certain object
during a given time interval - the relevant servers depend on actual
movement of the queried object. Therefore, efficient routing
mechanisms for trajectory-based queries are an important challenge
in SP-MODs. In this paper, we present the Distributed Trajectory
Index (DTI) that allows for such efficient query routing by creating
an overlay network for each trajectory. We further present an
enhanced index called DTI+S. It accelerates the processing of
queries on aggregates of dynamic attributes, like the maximum speed
during a time interval, by augmenting DTI with summaries of
trajectory segments. Our simulations with a network of 1000 database
servers show that DTI+S can reduce the overall processing time by
more than 98%.
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