Tableau Data Extract (TDE) is a snapshot of the data that Tableau stores locally. Good for very large
datasets of which we only need few fields. Performance is optimised because it queries its own
database engine instead of the local data source.
When you create an extract of your data, you can reduce the total amount of data by using filters and
configuring other limits. After you create an extract, you can refresh it with data from the original
data. When refreshing the data, you have the option to either do a full refresh, which replaces all of
the contents in the extract, or you can do an incremental refresh, which only adds rows that are new
since the previous refresh.
Extracts are advantageous for several reasons:
1) Supports large data sets: You can create extracts that contain billions of rows of data.
2) Fast to create: If you're working with large data sets, creating and working with extracts can be
faster than working with the original data.
3) Help improve performance: When you interact with views that use extract data sources, you
generally experience better performance than when interacting with views based on connections to
the original data.
4) Support additional functionality: Extracts allow you to take advantage of Tableau functionality
that's not available or supported by the original data, such as the ability to compute Count Distinct.
5) Provide offline access to your data: Extracts allow you to save and work with the data locally when
the original data is not available. For example, when you are traveling.
