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Unformatted text preview: 1 Database management Systems, 3ed, R. Ramakrishnan and J. Gehrke 1 Spatial Data Management Chapter 28 Database management Systems, 3ed, R. Ramakrishnan and J. Gehrke 2 Types of Spatial Data Point Data Points in a multidimensional space E.g., Raster data such as satellite imagery, where each pixel stores a measured value E.g., Feature vectors extracted from text Region Data Objects have spatial extent with location and boundary DB typically uses geometric approximations constructed using line segments, polygons, etc., called vector data . Database management Systems, 3ed, R. Ramakrishnan and J. Gehrke 3 Types of Spatial Queries Spatial Range Queries Find all cities within 50 miles of Madison Query has associated region (location, boundary) Answer includes ovelapping or contained data regions Nearest-Neighbor Queries Find the 10 cities nearest to Madison Results must be ordered by proximity Spatial Join Queries Find all cities near a lake Expensive, join condition involves regions and proximity 2 Database management Systems, 3ed, R. Ramakrishnan and J. Gehrke 4 Applications of Spatial Data Geographic Information Systems (GIS) E.g., ESRI’s ArcInfo; OpenGIS Consortium Geospatial information All classes of spatial queries and data are common Computer-Aided Design/Manufacturing Store spatial objects such as surface of airplane fuselage Range queries and spatial join queries are common Multimedia Databases Images, video, text, etc. stored and retrieved by content First converted to feature vector form; high dimensionality Nearest-neighbor queries are the most common Database management Systems, 3ed, R. Ramakrishnan and J. Gehrke 5 Single-Dimensional Indexes B+ trees are fundamentally single-dimensional indexes. When we create a composite search key B+ tree, e.g., an index on <age, sal> , we effectively linearize the 2-dimensional space since we sort entries first by age and then by sal. Consider entries: <11, 80>, <12, 10> <12, 20>, <13, 75> 11 12 13 70 60 50 40 30 20 10 80 B+ tree order Database management Systems, 3ed, R. Ramakrishnan and J. Gehrke 6 Multidimensional Indexes A multidimensional index clusters entries so as to exploit “nearness” in multidimensional space....
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- Spring '07
- Data Management, Database management system, R. Ramakrishnan, J. Gehrke, R-tree