What is Power BI doing when it is "evaluating" during a refresh?

[psmith-nhs-inc]

It seems like it is running the query it is evaluating, then running it again when retrieving records.  Which means it is taking twice a long as it should in order to get data.  

That would not make any sense, though.  So what exactly is happening when Bi is evaluating a query?

Phil

[v-yulgu-msft]

Hi @psmith-nhs-inc,

What do you mean "it is taking twice a long"? Do you mean the query is executed twice? Could you provide more detailed information about your scenario? What is your data source? Is there any query reference?

Regards,
Yuliana Gu

[psmith-nhs-inc]

I mean it seems like Refresh in Desktop runs every query twice.  It looks like it runs it once during the "evaluation" and then again to actually load the records into the database.

My data source n this case is an ODBC connection to a MYSQL database.  Under those conditions, what exactly is power BI doing when it is "evaluating" each and every query?

[psmith-nhs-inc]

So no-one knows what Power Bi Desktop is doing when it says it is evaluating a query?