3dcitydb
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3dcitydb
Purpose of "datatype" column?
the datatype should be given as a qualified datatype name from the CityGML schema (e.g. gml:GenericName, gml:DateTime)
according to this doc https://github.com/tum-gis/3dcitydb-v5/blob/master/docs/meeting_recordings/2021_10_19_3DCityDB_Version_5.0_Kolbe.xlsx
I see the following issues:
- I think we should keep the database free from encoding-specific stuff like GML type names. We could store the type name as defined in the conceptual model - but that implicitly follows from the qualified name of the property already.
- The type name is stored redundantly with every instance of a property. This will let the property table grow. We should have a good use case why we need this.
This needs more discussion.
It is a column to keep properties decomposable. For example. lod2Solid properties in the table have namespace values as "core", name values as "lod2Solid" and they have "gml:Solid" as datatype values. So, feature_id, namespace, name and index numbers are enough to define/differ geometries, but they are still keeping gml definitions on same table.
Not sure whether this speaks in favor of keeping or dropping the colunm?
In any case we should keep this independent from GML.
I feel myself very conservative at this moment :) So, i prefer to keep datatype column.
For the same reason I would drop it because we didn't have it in v4 and I never missed it :-) We can keep this issue open to collect use cases and reasons for having the column.
In your example, note that the data type of the "lod2Solid" attribute is not "gml:Solid" but "gml:SolidPropertyType". And this property type can be used to either store a "gml:Solid" or a "gml:CompositeSolid". So, if you want to store "gml:Solid" as information here, then you want to store the name of the attribute value not of the data type. That's a difference. The value is available from the geometry_data table.