PowerBI dataflow by default export a static file name, which is a great option, if you want only to overwrite the result.

now if you want to keep the history and partition the data, a very simple solution is to add a dynamic attribute to the file name, for example

let's say you have a date column in your data, you generate a file Export_2020_01_01

in next refresh, if there is a new data, it will generate a new file Export_2020_01_02, otherwise it will overwrite the previous file.

the attribute is not necessary a date , it can be anything, for example Export_Country1, Export_Country2 etc

I know about snapshot in the current implementation, which is different thing, as it add a time stamp to the file.