Why does bi-directional makes dax query performance slow

[Anonymous]

I have a set of tables (a,b,c,d), which have the following relation. Please note that this is not my own design.

A->B

C->B

B-->D Bi-directional

When I run a  dax query with just down a sum(x), with the Bi-Directional turn-on, the query runs in 12 seconds and creates 67 queries.

When I run the same dax query with Many-One relation (turn off bi-directional), the query runs in 1.7 seconds and it create 12 queries only.

Any ideas.

[amitchandak]

Bi-direction relation, allows you to filter on both sides and it means you will lot more stuff to filter in. 

Refer

https://www.sqlbi.com/articles/bidirectional-relationships-and-ambiguity-in-dax/

https://radacad.com/what-is-the-direction-of-relationship-in-power-bi

https://community.powerbi.com/t5/Desktop/Bi-Directional-Relationships-good-or-bad/td-p/79707