Central Geodata Warehouse
Lately, it is getting more common in city and canton governments to
manage and update spatial data of all parts of the government in one central
data pool called geodata warehouse (a spatial database management system). This
makes huge savings as the data is now stored redundance free and needs to be
updated only once. Until now the some data needed to be stored and updated in
different departements of the government. This made it enormously difficult to
have current data at all places. Additionally, when doing bigger projects the
data can now simply be taken out of the geodata pool and does not need to be
gathered in tedious and lengthy work.
The most important
characteristics of such database systems:
Concurrent
Use
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A central geodata warehouse is a nice example of concurrent use of
a database system. On the one hand different users get their data from it -
the employees of the different departements. On the other hand different
application software (e.g. GIS systeme) are used to access the geodata
warehouse. Therefore, it is possible that the forestry departement uses GIS
software A for access to the data while the surveyor departement uses GIS
software B.
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Separation of
Data and Applications
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Like described above, different user with different applications
get access to the data. This is only possible, if the data is separated from
the applications. Would the data be connected to the application it would be
much work to process the data in way that other applications could read and
use it. This independence is especially import in cases where the DBMS
software needs replacement. With the separation of data and applications
this is possible without having to re-write all of the application
software. Example: A Microsoft Word file (where the data is
included in the application format) is quite difficult to open with the
Microsoft Excel software even though both applications are made by the same
company.
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Data
Persistence
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The capture of geodata
and other
data is most often a lot of work and very expensive. Therefore, data
persistence is a very important characteristic of a geodata warehouse. This
way, it is possible to ensure that data is not lost and needs then be
replaced costly. |
Data Integrity
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Governmental data often give information about legal conditions
like, for example, the cadaster. Therefore, these data need to be thoroughly
correct and reliable. That is achieved through the definition and following
of specific consistency requirements and rules.
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Schematic Representation of a Geodata Warehouse and the possible Access to it from different Offices