A dataset can be one of several different types. Dataset type is distinguished on the basis of data storage and structure and, since FME handles each type differently, it’s important to be aware of the differences and to know which type of data you are working with.
|File||a single file||AutoCAD DXF|
|Folder||a set of files in a single folder||Esri Shapefile|
|Database||a database||Oracle Spatial|
|Web||an Internet site||Web Feature Service (WFS)|
A file-based dataset is a complete dataset stored within a single file.
An AutoCAD DXF file is a good example of this: each DXF file is a separate dataset.
Feature Types within File-Based Datasets
File-based datasets usually have some method of assigning data to different categories. In FME, these categories are the different feature types.
For example, in an AutoCAD file, the data is defined in terms of a number of layers. Each layer in a DXF file is a feature type in FME. A DGN format file uses levels instead of layers.
The logic behind a folder-based dataset can be slightly confusing. In this form of dataset, the dataset is the folder or folder holding the data. For example, in C:\FMEData\Data\Properties the dataset name is Properties.
Esri Shapefile, MapInfo TAB, and CSV formats are examples of folder-based datasets.
Feature Types within Folder-Based Datasets
In a folder-based dataset, data is held as a series of files. Commonly, each differently named file is a feature type within the dataset.
For example, within the following MapInfo MIF/MID data structure, the dataset is called EastA. The feature types are BoundaryArea, HydrographyLine, and RoadLine.
Note: FME users commonly mistake all individual files for a dataset. When there is no method of subdividing the data within the file itself, FME usually treats the file as a feature type within a folder-based dataset.
A database dataset, as the name implies, is a set of data stored within a database. Generally each different database is a different dataset (although, to be strictly accurate, each user/schema within a database would be a different dataset).
The most obvious example is an Oracle database. It will be treated the same way whether it is spatial or non-spatial.
Feature Types within Database Datasets
In a database dataset, each different table within the database is treated as a feature type.
For example, an Oracle database called resources has tables called users, vehicles and equipment. The dataset is resources, the feature types are users, vehicles, and equipment.
A web dataset is a collection of data stored on an Internet site. A Web Feature Service (WFS) server is an example of this. In this case, the name of the dataset is the same as the name of the URL (Universal Resource Locator).
Feature Types within Web Datasets
Web datasets commonly have a number of layers. Each layer represents a different feature type. WFS format is one example of this type of dataset.