For a long time now when you wanted to filter multiple data sources you'd have to use a parameter in Tableau. This worked well but had is not without its own limitations. Namely, the limited parameter interface choices and the need to use a calculation to apply the filter.
Now in Tableau 10 you can achieve the same capability with an even better user experience using Cross Database Filters. I'm super excited about this as the maintenance issues with using parameters and calculated fields has plagued me more than once.
Video Tutorial
How To
- Build two or more views using different data sources
- In one of the data sources, add a filter
- Right click on the filter and choose “Apply to all related data sources”
- (optional) Adjust which data sources get the filter using Data > Edit Relationships