There are specific benefits to creating foreign table views, in addition to the usual reasons of security and hiding SQL complexity. These benefits include:
- Makes it easier to query object store data with inconsistent uppercase and lowercase field names. CSV field names are case sensitive, but Teradata SQL is case insensitive.
- You can hide the $path references in a foreign table and make path names look like standard column names.
Follow these recommendations when creating a view on a foreign table:
- Include both path names and payload attributes as columns in the view.
- CAST all values in the view to an appropriate data type.
- It is often the case that the path segment name (such as siteno in data / siteno / year / month / day) is also represented by an attribute in your data. When this is true, Teradata recommends you equate them in the WHERE expression in the view and only specify one of them in the column list. For example, see the use of TheSite in the example view here: Using a Foreign Table View with Path Filtering.