What is the mechanism of Power BI Loading data

[martinhyy]

Hi 

I'm really curious why loading some data in power BI can sometimes take so long? I'm an R user and also efficient with Excel. When I query and load data from R or open some data in Excel, most of the time, the load can be instance (even loading a few millions rows of data in R doesn't take really this long). When I try to do the same thing in Power BI, Power BI  keeps evaluating and loading the data for a long time. Then after I change the filter and want to apply the change, it takes another long time again.

1) I wonder what is Power BI doing when the screen says "Evaluating"?

2) Why in other software, filtering or loading data can be really fast, while in Power BI it takes tremendous long time?

3) When Power BI decides the type of the fields, I was told it only sample the first few thousand rows (or something like that) to decide the data type. What stops it from scanning through the whole data set and decide the data type?

4) Is there a way to download one whole raw data frame from Power BI? Sometimes I need to reconcile the data queried from Power BI connector with a local spreadsheet. When the data gets to large, it only export part of the data from table visualization.

Really appreciated for any answers or suggestions

Thanks 

[v-ljerr-msft]

Hi @martinhyy,

---

---

4) Is there a way to download one whole raw data frame from Power BI? Sometimes I need to reconcile the data queried from Power BI connector with a local spreadsheet. When the data gets to large, it only export part of the data from table visualization.

I am only able to answer the fourth question. Currently, there is a limitation that data used by the R visual for plotting is limited to 150,000 rows. If more than 150,000 rows are selected, only the top 150,000 rows are used and a message is displayed on the image. Here is the idea to remove this limitation. You can vote it up and add your comments there to improve Power BI on this feature. 

Regards

[martinhyy]

Thanks @v-ljerr-msft

Just voted. Also thanks for your response. Hope we can see this feature soon. 🙂