Adding a column to logical table or logical table source

yaseennawaz

Hi ,

Can anyone explain in which scenario do we add a column in physical layer to a logical table and in which scenario do we add it to a logical table source?

Regards,

Yaseen

SriniVEERAVALLI

for a instance : a new custom column  is added to OOB box or existing table in database and that column you need to have in reports.

As project demands assume that you need to go for an aggregate table in that case you'll go for logical table source for existing fact table in BMM.

these 2 are just tip of iceberg

Gianni Ceresa

yaseennawaz wrote:

... in which scenario do we add a column in physical layer to a logical table and in which scenario do we add it to a logical table source?

It sounds a bit confusing ...

You can't add a column to a logical table source (LTS) as this doesn't mean anything, but when you add a logical column to your logical table (dim or fact is the same) you must also define how this column does get some data. If it represent data coming from your physical sources you must map this column to through the logical table source to a physical column (or a formula defined in the LTS.

So you never really add a column to a LTS but you can only map columns through LTS. A logical column can also be derived from other logical columns and in that case the logical column doesn't have any definition in any LTS.

Going back to your question:

- in which scenario do you add a column coming from your physical layer to a logical table? When you want to do something with that column and most of the time expose it in a subject area.

- in which scenario do you add a column coming from your physical layer to a LTS? Never, as you can only map existing logical columns in a LTS (if you drag & drop it will first create the logical column and only after map it in the LTS to the physical one you dragged).