Difference in coumn source types in BMM layer

Question

Hi All,

Can you please clear me on one thing? What it makes a difference if I define ABC column from "Derived from existing columns using an expression" or if the same column if defined as "Derived from physical mappings"? What will be the difference in queries getting generated by a bi_server?

[Deleted User] · Answer

You're welcome. Common pitfall as soon as you start calculating weighted averages or the likes.

Sagar Tippe · Answer

Hello Christian,

thanks a lot as usual.. you came to rescue.. to clear doubts from the basics.. thanks for the answer and many thanks for that particular doc in the link.. that was fab info.....

[Deleted User] · Answer

Physical = pre-aggregation execution. i.e. executed row-by-row.

Derived logical = post-aggregation execution. i.e. executed on result sets.

Ref slide 15 https://www.slideshare.net/ChristianBerg8/50-shades-of-fail-kscope16