SAP BW Faqs part -I

What is compression?
• It is a process used to delete the Request IDs and this saves space.

What are the options available in transfer rule and when ABAP code is recquired during the transfer rule what important variables you can use?
A: Assign info object, Assign a Constant , ABAP routine or a Formula

When you write user exit for variables what does I_Step do?
A: I_Step is used in ABAP code as a conditional check.

What is the table that is used in start routines?
• Always the table structure will be the structure of an ODS or InfoCube. For example if it is an ODS then active table structure will be the table.

Explain how you used Start routines in your project?
• Start routines are used for mass processing of records. In start routine all the records of DataPackage is available for processing. So we can process all these records together in start routine. In one of scenario, we wanted to apply size % to the forecast data. For example if material M1 is forecasted to say 100 in May. Then after applying size %(Small 20%, Medium 40%, Large 20%, Extra Large 20%), we wanted to have 4 records against one single record that is coming in the info package. This is achieved in start routine.

What are Return Tables?
• When we want to return multiple records, instead of single value, we use the return table in the Update Routine. Example: If we have total telephone expense for a Cost Center, using a return table we can get expense per employee.

How do start routine and return table synchronize with each other?
• Return table is used to return the Value following the execution of start routine

What is the difference between V1, V2 and V3 updates?
• V1 Update: It is a Synchronous update. Here the Statistics update is carried out at the same time as the document update (in the application tables).
• V2 Update: It is an Asynchronous update. Statistics update and the Document update take place as different tasks.
o V1 & V2 don’t need scheduling.
• Serialized V3 Update: The V3 collective update must be scheduled as a job (via LBWE). Here, document data is collected in the order it was created and transferred into the BW as a batch job. The transfer sequence may not be the same as the order in which the data was created in all scenarios. V3 update only processes the update data that is successfully processed with the V2 update.

What is Rollup?
• This is used to load new DataPackages (requests) into the InfoCube aggregates. If we have not performed a rollup then the new InfoCube data will not be available while reporting on the aggregate.

How would you optimize the dimensions?
A: Use as many as possible for performance improvement; Ex: Assume that u have 100 products and 200 customers; if you make one dimension for both ,the size of the dimension will be 20000; if you make individual dimensions then the total number of rows will be 300. Even if you put more than one characterstic per dimension, do the math considering worst case senerio and decide which characterstics may be combined in a dimension.