Power BI Refresh

Hello

I am dealing with Power BI refresh issue in my organization. I want to clear one thing How exactly power BI reftesh is working?

We are using SSAS to import data to Power BI and then we make reports and publishing it. Our basic work flow for data is data coming from Teradata to SSAS Tabular and From SSAS tabular to Power BI. So for e.g whenever tabular refreshes and 2 new record is updated in Tabular model so after that when Power BI refreshes do power BI will take only 2 new updated data or it will refresh whole Tabular Database. (So Power BI will do only incremental refresh or whole refresh)

Thank You