[xquery-talk] xquery and geospatial request
kennorth at sbcglobal.net
Fri Jun 1 13:08:20 PDT 2007
> I need to store GML feature in a database and to be able to make geospatial
> request on them.
> Do we have a language (extension to xquery) to make such request on a XML
> native database ?
For an engine to store and retrieve geospatial data, it needs to operate with
metadata for geospatial information and use something like R-tree indexing to
provide query performance. Then there might be a requirement to do content-based
image retrieval and support OpenGIS data types.
Support for geospatial processing has matured in platforms such as Informix
Spatial DataBlade, Oracle Spatial, DB2 Spatial and ESRI SDE. It would be
bleeding edge for a native XML database with limited indexing capability.
(B-tree indexing is adequate for alphanumeric types but not for geospatial
Oak Ridge National Labs has done some interesting work on indexing geospatial
data. It uses a markup agent to create an XML file with properties and metadata
for each satellite image. Another agent uses those XML files when analyzing the
images to create feature vectors for segment clustering and index creation.
You might want to look at something like the PostGIS extension for PostgreSQL.
It's used for GeoServer, available with a GPL license, and supports R-tree
indexing. There's also an open source product for using spatial types with
Microsoft SQL Server. A client seems happy with the Java Topology Suite and
GeoTools, which includes a GML parser.
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