You’ll often hear people talking about Secondary (Thin) Reports in Power BI circles, but their full power and value often aren’t explained or fully expressed. One of the strengths of Power BI is the portability of DAX, i.e. a measure does not bring context with it; the context is applied when it is used. You can use total Sales with months for Monthly sales, Products for product sales months and products for product sales per month; the list goes on. Secondary Reports are the same. They are an instruction set for visualisations. This means they are not explicitly tied to a data model. This means that when you upgrade your data models, your can bring your Secondary Reports along, so they do not all have to be recreated from scratch.
Migrating Secondary Reports is relatively simple, and you have to understand a couple of things;
- Vertipaq – Be prepared to explore Vertipaq Analyser to get the DAX statements used by the Primary Report Data model that is currently used (this will be needed for the visualisations to work). In our example we had the “Total Passengers” measure to migrate into the new data model. Measures do not need to have the same name but you should figure out what will map to what. NOTE – if your secondary report has any internal DAX statements you may want to promote these to the main data model now.
- View – It is advisable to have the report open in the service while you are remapping it, so you can see what it looks like. You see how the report content can just disappear (I deliberatly set this up to work like that so you would see the worst case scenario – it depends on how much the model has changed and measure name changes)
- Don’t click “Fix now” – no matter how basd things get don’t be tempted to click “fix now”, this just removes the broken elements from your visual, the impact of this is that you cannot necesarily see why it isn’t working. The warning signs shown in the filter and visual field well are your cues for action.
Now you know what you do; it is as simple as remapping the connection and then going visual by visual to fix it. Our three-page report took less than ten minutes to migrate.
Don’t forget to watch the support video as well
