This will be a short post, but I didn't want to gloss over this new feature in Foglight Cloud 7.3.1.
SQL Performance Investigator (SQL PI) keeps workload data for two years, but there will be different granularity levels depending on the age of the data.
The top right of the screen now shows the generations of data that you're looking at in SQL PI.
If the time range selected involves multiple generations of data, those will be available when you hover over the "i" icon.
That's it, short and sweet. But it should help with understanding the data backing up the workload investigation.