Databases

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A geodatabase is a spatial database designed to store, query, and manipulate geographic information and spatial data of low dimensionality. It is a specialized type of spatial database often with optimizations for 2 and 3 dimensions, raster data and Euclidean distance.

Within a spatial database, spatial data is treated as any other data type. Vector data can be stored as point, line or polygon data types, and may have an associated spatial reference system. A geodatabase record can use a geometry data type to represent the location of an object in the physical world and other standard database data types to store the object's associated attributes. Some geodatabases, such as Rasterlite (Rasterlite, 2012)[1] and those used by ESRI in their ArcGIS software, also include support for storing raster data.

Many geodatabases have custom functions that allow the spatial data to be manipulated and queried using SQL, for example to find all the residents of an area within an exposure zone for a potential environmental hazard. However the spatial data in some geodatabases can only be accessed by using specialized client software.

Within a geographic information system (GIS) a spatial database is one component that can be used to store and manipulate data. Typically a complete system will also include client software to view and edit the data stored within the database. Like other spatial data formats geodatabases can also be used to serve data directly to web map server software, such as ESRI's ArcGIS Internet Map Server, MapServer and Google's mapping API. The term GIS-Centric, however, has been specifically defined as the use of the Esri ArcGIS geodatabase as the asset/feature data repository central to Computerized Maintenance Management System (CMMS) as a part of Enterprise Asset Management and analytical software systems. GIS-centric certification criteria has been specifically defined by NAGCS, the National Association of GIS-Centric Solutions. http://www.nagcs.org/index.asp

The primary advantage of spatial databases, over file-based data storage, is that they let a GIS build on the existing capabilities of relational database management systems (RDBMS). This includes support for SQL and the ability to generate complex geospatial queries. Also, a database's client/server architecture supports multiple users simultaneously and lets them view, edit, and query the database without conflict (Wikipedia, 2012) [2].

Examples

Opensource Components
  1. The CEOS Missions, Instruments and Measurements database online - http://database.eohandbook.com/index.aspx.
  2. CEOS System Database.
  3. 3VMDS 3VIDS manages data store from smallworld.
  4. Spatial Query Server|Boeing's Spatial Query Server spatially enables Sybase ASE.
  5. IBM DB2|DB2 – Allows spatial querying and storing of most spatial data types.
  6. Informix – Allows spatial querying and storing of most spatial data types.
  7. Microsoft SQL Server – The latest player in the market of storing and querying spatial data. At this stage only some GIS products such as MapInfo and Cadcorp SIS can read and edit this data while ESRI and others are expected to be able to read and edit this data within the next few months
  8. Oracle Spatial – Product allows users to perform complex geographic operations and store common spatial data types in a native Oracle environment. Most commercial GIS packages can read and edit spatial data stored in this way.
  9. PostGIS – a spatial database based on the free PostgreSQL database

References

  1. Rasterlite, 2012. [online]http://www.gdal.org/frmt_rasterlite.html
  2. Wikipedia, 2012. [oline] http://en.wikipedia.org/wiki/Databases