Tableau 10 introduces the ability to join data across data connections. This means you can join tables of data from completely different database and file formats. For example, you could join a table in SQL Server with a union table of text files with a Google Sheets document.
You'll recall that the concept of joins and the specifics of cross-database joins were introduced in Chapter 2, Working with Data in Tableau. While cross-database joins are quite useful in bringing together disparate data sources (data contained in different systems and formats), they can be used to solve other data issues too, such as reshaping data to make it easier to meet your objectives in Tableau.