Chris Webb provides an explanation:
I have always wondered what the partialBatch option for the commitMode parameter in the Enhanced Refresh API does exactly. There is some documentation here and here but I was curious to find out more as part of the research I’m doing for my ongoing series on Power BI refresh memory errors, in case it was useful for reducing overall memory usage (spoiler: it may be). In this post I’ll share what I found out after running some tests.
Read on for the demonstration and explanation, as well as tips on when you might want to use it.