Tableau Prep is a powerful tool but it can’t help solve every data preparation scenario. We focus a lot of our time and effort on what it can do, but we thought it would be worthwhile to cover what it can’t do (yet).
Since it is still in a version one, the product has limitations. A few of those include the variety of data sources you can connect to (less than 30), limited output options (.tde, .hyper and .csv only) and the inability to automate a flow.
Those aside, let’s looks at three data preparation scenarios where you’ll need more than just Tableau Prep:
● Comparative Row Calculations
● Adding a New Column of Data
● Unpivoting (Transposing) Data
Comparative Row Calculations
If you have a situation where you need to sort your data and calculate the difference between one row and the next, Tableau Prep is not able to help with that at this point. Take below as an example. If you have a column for date and a column for account balance and you want to calculate the difference from one date to the next, Tableau Prep can’t do that.
New columns of data can be created in Tableau Prep, but they work much like calculated fields in Tableau Desktop. They can only manipulate existing fields. If you want to add a new column for something like Record ID (typically an INDEX function in Tableau Desktop) that isn’t possible. As a general rule, Tableau Desktop table calculation functions can’t be used in Tableau Prep.
Unpivoting (Transposing) Data
Occasionally you may come across data sources where the data need to be unpivoted or transposed. Take the following as an example.
Each metro area has three related indexes, but those indexes are each a row, not a column. Each index needs to become its own column (along with the dates needing to be pivoted, but that’s a different story). There are workarounds to do this in Tableau Prep, but it’s not a native feature. If you are talking about a lot of measures, unpivoting one by one will not be feasible.