Hopefully someone can help me out with a problem I'm working through. Currently running Tableau 9.2.
We have an enterprise data source that is an SSAS Tabular model. I have some extra supplemental data in a CSV file that I would like to join to one of the common fields between the two so I can pull some of the SSAS measures by the supplemental data's dimensions that I've blended.
When I do the join between the SSAS Tabular Model (primary data source) and the CSV file, it works whenever I'm pulling no measures from the primary data source. I can pull related dimensions between the two and see the relationship working. However, as soon as I try to pull in a measure from the primary SSAS tabular model source, I get the error "Cannot blend secondary data source because one or more fields use an unsupported aggregation".
This is still a limitation in Tableau 10.0. I would upvote the idea and encourage others to do the same. I'm not sure about using custom mdx but I do know that other users have funneled data from cubes to other friendly databases and had success with blending.