On-Prem Gateway, is my understanding correct?

[CarlInglis]

It's my understanding that, when using an ODBC connection, the Gateway will receive the entire set of results from the data source, compress and encrypt it, and then post it back to Service Bus.

Am I correct in this understanding, especially it needing to get the entire set of results back before it passes them on?

Any links to documents I can use to prove (or disprove) this would be much appreciated - a somewhat heated discussion needs to be resolved.

Thanks!

[Greg_Deckler]

@CarlInglis - Pretty sure that you are correct on the essential elements of this. Your best bet for official documentation will be these white papers. I would go through the Security one.

https://docs.microsoft.com/en-us/power-bi/guidance/whitepapers

[CarlInglis]

Hi Greg, thanks for the link.

The security white paper talks about the Gateway role within the service itself, but doesn't discuss the On-Prem Gateway.

I'll have a look through the other whitepapers in case there's something useful, and if there is then I'll followup to this.

Thanks again.

[nickyvv]

Hi @CarlInglis,

an ODBC source also supports (limited) Query Folding. This is the concept of pushing transformations back to the source.

I'm not familiar with any ODBC datasource we use, so I haven't tried this, but I assume basic transformations like filtering or selecting columns would result in pushing back those (simple) transformations to the ODBC source, so it will return less data in this instance.

You can check this with the "newish" feature in Power Query called Query Diagnostics.

[aj1973]

I confirm ODBC supports very limited Query Folding. I built a report using ODBC connection, the work arround would be an M Code, or SQL Query applied directly in the source of your table under "more options"