Resident Load usage

[pradeep92]

Hi,

I am having a data like ,

Product:

LOAD ProductID,

     [Product name],

     Sales,

     [Modified date],

     [Product country],

     Export,

     Sales*ProductID as Ex  // made own transformation

FROM

Incremental.qvd;

I know resident load can load data from previous existing data,make transformations and calculations etc.. but when is the situation to use it bcz i know i can directly make calculations in the loaded data itself ?