Databases Reference
In-Depth Information
Multimedia DB
Spatial info
Temporal info
2D R-tree
1D R-tree
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Figure 8.1
A simple (spatial and temporal) indexing scheme.
the merging of the two indexes (the spatial and the temporal one) in a unified
mechanism. This scheme is proposed next.
A Unified Spatiotemporal Indexing Scheme
We propose a unified spatiotemporal indexing scheme that eliminates the
inefficiencies of the previous scheme and further improves the performance
of an IMD tool. The proposed indexing scheme consists of only one index: a
spatial (three-dimensional) index for the complete spatiotemporal information
(location in space and time coordinates) of the objects. If we assume that the
R-tree is an efficient spatial indexing mechanism, then the unified scheme is
illustrated in Figure 8.2. The main advantages of the proposed scheme, when
compared to the previous one, are the following.
The indexing mechanism is based on a unified framework. Only one
spatial data structure (e.g., the R-tree) needs to be implemented and
maintained.
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Spatiotemporal operators are more efficiently supported. Using the
appropriate definitions, spatiotemporal operators are implemented
as three-dimensional queries and retrieved using the three-
dimensional index, so the need for (time-consuming) spatial joins is
eliminated.
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