Understanding RLS Security Filter in Both Directions

[YuanQingTan]

I wasn't able to find any clear explanation on how the security filter in both directions work.

After reading on the web, I did my own testing with the materials from MS Learn Power BI Lab and had a better understanding of why is this option helpful.

Heres what I found

Try to modify the file from lab 10: 10-Solution-Sales Analysis.pbix as per the screenshot below.

Only the tables shown is important and only the relationships highlighted yellow are important. 
The other tables can be hidden.

The existing RLS is applied to the Salesperson Performance Table on the UPN.

Referring to the screenshots below

In the first box, the role is set to none, the two matrix visuals show all the sales by region and salesperson in different order.

We can see that StephenJiang has 6 Regions.

In the second box, the "security filter in both direction" is DISABLED for the relationship between Region and SalespersonRegion (marked with Δ in the screenshot above).

Role is set to StephenJiang

From this we can see that the sales for other regions are also shown if the [Region] comes before [Salesperson] in the visual.
If the order is reversed, we only see the regions for StephenJiang

In the third box, the "security filter in both direction" is ENABLED.

From this we can see that only the sales of regions corresponding to StephenJiang is shown regardless of whether [Salesperson] or [Region] comes first in the visual.

[suparnababu8 · Accepted solution]

Hi @YuanQingTan 

You may go through this https://community.fabric.microsoft.com/t5/Desktop/What-does-it-mean-to-apply-a-security-filter-in-bo... url for solution by @Anonymous 

Microsoft documnetation link - https://learn.microsoft.com/en-us/power-bi/guidance/rls-guidance