Frequently Asked Interview Questions in SAP BW

1. How would you optimize the dimensions?

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 characteristic per dimension, do the math considering worst case scenario and decide which characteristics may be combined in a dimension.

2. What are the conversion routines for units and currencies in the update rule?

Time dimensions are automatically converted; ex: if the cube contains calendar month and your transfer structure contains date, the date to calendar month is converted automatically.

3. Can you make an infoobject as info provider and why?

Yes, When you want to report on characterstics or master data, you can make them as infoprovider. Ex: you can make 0CUSTMER as infoprovider  and do Bex reporting on 0CUSTOMER;right click on the infoarea and select ‘Insert characterstic as data target’.

4. What are the steps to unload non-cumulative cubes?

1. Initialize openig balance in R/3(S278)
2. Activate extract structure MC03BF0 for data source 2LIS_03_BF
3. Setup historical material docus in R/3
4. Load opening balance using data source 2LIS_40_s278
5. Load historical movements and compress without marker update.
6. Setup V3 Update
7. Load deltas using 2LIS_03_BF

5. Give step to step approach to archiving cubex?

• Double click on the cube (or right click and select change)
• Extras -> select archival
• Choose fields for selection (like 0CALDAY, 0CUSTOMER.etc)
• Define the file structure (max file size and max no of data objects)
• Select the folder (logical file name)
• Select the delete options (not scheduled, start automatically or after event)
• Activate the cube
• Cube is ready for archival

6. What is data target administration task?

Delete index, generate index, construct database statistics, initial fill of new aggregates, roll up of filled aggregates, compression of the InfoCubes, activate ODS, complete deletion of data target.

7. What are the parallel process that could have locking problems?

• Hierarchy attribute change run
• Loading master data from same infoObject; for ex: avoid master data from different source systems at the same time.
• Rolling up for the same info cube.
• Selecting deletion of info cubes/ ODS and parallel loading.
• Activation or deletion of ODS object when loading parallel.

8. How would you convert an info package group into a process chain?

Double Click on the info package grp, click on the ‘Process Chain Maint’ button and type in the name and description ; the individual info packages are inserted automatically.

9. What are the data loading tuning one can do?

• Watch the ABAP code in transfer and update rules;
• Load balance on different servers
• Indexes on source tables
• Use fixed length files if u load data from flat files and put the file on the application server.
• Use content extractor
• Use PSA and data target in parallel option in the info package
• Start several info packagers parallel with different selection options
• Buffer the SID number ranges if u load lot of data at once
• Load master data before loading transaction data.

10. What is the use of BW Statistics?

The sets of cubes delivered by SAP is used to measure performance for query, loading data etc. it also shoes the usage of aggregates and the cost associated with then.

11. What are the options when defining aggregates?

* – groups according to characteristics

      H – Hierarchy

      F – fixed value

      Blank — none

12. How will you debug errors with SAP GUI (like Active X error etc) ?

Run Bex analyzer -> Business Explorer menu item -> Installation check; this shows an excel sheet with a start button; click on it; this verifies the GUI installation ;if u find any errors either reinstall or fix it.

13. How do you replace a query result from a master query to a child query?

If you select characteristic value with replacement path then it used the results from previous query; for ex: let us assume that u have query Q1 which displays the top 10 customers, we have query Q2 which gets the top 10 customers for info object 0customer with as a variable with replacement path and display detailed report on the customers list passed from Q1. [/social locker]

14. What are the data target administration tasks?

Delete index, generate index, construct database statistics, initial fill of new aggregates, roll up of filled aggregates, compression of the InfoCube, activate ODS, complete deletion of data target.

15. What are the other BW processes?

• Attribute change run
• Adjustment of time dependent aggregates
• Deletion of requests from PSA
• Reorganize attributes and texts for master data – this is a useful tool to compress master data and text.

16. What are the parallel processes that could have locking problems?         

• Hierarchy attribute change run.
• Loading master data for same info object; for example avoid loading master data from different source systems at the same time rolling up for same infocube.
• Selecting deletion of info cube/ODS and parallel loading.
• Activation or deletion of ODS object when loading parallel.

17. What is ODS?

Operational Data Source: It used for detailed storage of data (like document level); you can overwrite existing data in ODS (in cube you cannot); you can also drill down-from cube to ODS; It is used for data consolidation and cleansing; the data is stored in a flat table (unlike the extended star schema of the cube);-so using SE11/SE16 you can query the ODS data directly.

18.  What are the advantages of using ODS in a infoset for reporting?

• Access via OLAP engine.
• Infosets can Join flat BW objects- like master data attributes, etc

19. What is the new features of ODS after version 3.x?

• you can load and activate ODS in parallel
• No M table
• Secondary indexes are created in CDS objects itself
• Selective deletion

20. What is the use of BW statistics?

• The sets of cubes delivered by SAP is used to measure performance for query, loading data etc. it also-shows the usage of aggregates and the cost associated with them.
• Gives data on aggregates, OLAP and Warehouse management.

21. How do you install BW statistics?

Use the business content to install. Using the Business Content section of AWB, select info area “BW Statistics”; right click and select insert objects for collections; select before and after data flow for grouping and install. Similarly install the Technical Content SAP_BW_TCONT role. Install the info package groups for Master data/text and transaction data.

22. Give some examples’ of jqueries delivered with BW statistics?

• Mean time pdr query
• Runtime query
• Using iufocubes
• Utilizing OLAP