"Publish" button: What is actually being sent??

[Anonymous]

I have a huge uncertainty of how the "Publish" button on Power BI Desktop application works.

If I create a report on Power BI Desktop via a local file(.csv) and then proceed to hitting "Publish":

• What exactly is being pushed to Power BI?
• If the data I am referencing is a local data file(.csv), is that data being pushed to Power BI or is it just the visualizations?
• How does this work if the reports are referencing data from SQL Server?

I would not think I would be publishing 3GBs of into to Power BI.

Thanks.

[AB-Learner]

@MattAllington You write that "There are 2 modes for Sql server.  You can use direct query mode (data stays in the server locally) or import mode (data is copied just like csv files).".  If the direct query mode is used on your 60GB sql database, then why is there still a 300MB size?  Does it mean that the direct query still "imports" all the required data into the powerBI service?

[MattAllington]

The short answer is compression. If you have date/time columns in your database, make sure you turn off auto date/time in Power BI and this will help further (it's under settings, current workbook and also under global settings. You can turn them both off).  I have a workbook I use as a demo in my training course "Demystifying DAX" that contains a table with 1 column, 2 billion rows of string data (A or B). This workbook is about 15kb from memory. It would be GBs in SQL.  It's a big topic, but columns of data with a low number of unique values compress really well. 

Here's the course if you're interested. https://skillwave.training/shop/demystifying-dax/

[AB-Learner]

Thanks.  

[MattAllington]

Power bi desktop ingests a full copy of the data. The connection is no longer needed (unless you want to refresh the data). The copy of the data is sent to the power bi service along with the model and the visualisations. 

There are 2 modes for Sql server.  You can use direct query mode (data stays in the server locally) or import mode (data is copied just like csv files).  

It is unlikely that you would need 3gb of data copied to a power pivot workbook. I have a 60gb sql database that loads to 300mb by the time I have loaded just the data I need and also the compression has done its job