sap bi and bw interviewquestions

7/27/2019 Sap Bi and Bw Interviewquestions

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SAP BI/BW Interview Questions

and Answers

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1. What is BW Statistics and how is it used?

The set of info cubes delivered by SAP as a part of SAP BIW which are useful in measuring the performance of howquickly a query is calculated, or how quickly data in loadedinto BW and so on. BW statistics are the name suggest are

useful in showing data about the costs associated with BWqueries, aggregative data, OLAP, SAP business warehousemanagement.



2. In Data Ware housing what are the nine

decision points used in BW ? The nine Decision Points of Data Warehousing are:

Identify Dimension Tables.

Identify Attributes of entities.

Define granularity of the fact table.

Pre Calculated Key figures.

Slowly changing dimensions.

Define attributes of entities. How long data will be kept.

Aggregates.

How often data is extracted.



3. How the dimensions are optimized?

It system can be used as many as possible for performance,for instance it may be assumed that 100 products and 200customers; if one dimension for both, the size of thedimension will be 20000; if it was made individual

dimensions then the total number of rows will be 300.Even if they are taken more than one characteristic perdimension, the math considering worst case and decide

which characteristics may be combined in a dimension.



4. As per the update rule what are theconversion routines for units and currencies?

As per the update rule, the Time dimensions areautomatically converted for example if the cube containscalendar month and the transfer structure contains date,the to calendar month is converted automatically.



5. What are the advantages of SID table?

The SIC table Surrogate ID table is the interfacebetween master data and the dimension table, and theadvantages are:

Uses Numeric as indexes for faster access.

Master Data independent of info cubes.

Language support.

Slowly changing dimension support.



6. How can an info object as info provider and why?

When the report on characteristics or master data, it canmake them as info provided for example make CUSTOMER

as info provided and do Bex reporting on CUSTOMER,right click on the info area and select “Insert Characteristicas data target”.



7.What other tables are created for master data?

The tables that are created for master data are: M view – Combines P and Q tables.

P table – Time independent master data attributes.

Q table – Time Dependent master data attributes.

X table – Interface between master data SID and timeindependent navigational attributes SID where P is linkedto the X table.

Y table – Interface between master data SID and timedependent navigational attributes SID where Q is linked tothe Y table



8. What steps are involved to upload non cumulative

cubes? The steps that are involved to upload non cumulative cubesare:

Initialize opening balance in R/3 (S278).

Activate extract structure MC03BF0 for data source2LIS_03_BF. Setup historical material documents in R/3. Load opening balance using data source 2LIS_40_s278.

Load historical movements and compress without markerupdate. Setup V3 update. Load deltas using 2LIS_03_BF.



9. What are the load process and processing?

The load process and processing are the Info package, ReadPSA and update data target, save hierarchy, update ODSdata object, data export open hub, delete overlappingrequests.



10. What is the data target administration task?

The data target administration target is to delete index,generate index, construct database statistic, initial fill ofnew aggregates, roll up of filled aggregates, compression ofthe info cubes, activate ODS, complete deletion of data

target.



11. Give the Step to Step approach to archiving

cubes? The Step to Step approach to Archiving Cubes is: 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 maximum file size and maximum

number of data objects. Select the folder logical file name.

Select the delete options not scheduled, startautomatically or after event. Activate the cube.Cube is ready for archival.



12. When there is a locking problems what is the

parallel process? The parallel process for locking problems:

Hierarchy attributes change run.

Loading master data from same info objects, for exampleavoiding master data from different sources system at thesame time.

Rolling up for the same info cube.

Selecting deletions of info cube/ODS and parallel loading.

Activation or deletion of ODS object when loadingparallel.



13. What is the procedure to convert an info

package group into a process chain?

The procedure to convert an info package group into aprocess chain is by double clicking on the info packagegroup, click on the Process Chain Maintenance button andtype in the name and description, the individual infopackages are inserted automatically.



14. How can a cube partitioned for which the

data already exists? The cube cannot be partitioned if the data already existsthe cube must be empty to do this, one work around is tomake a copy of the cube A to cube B, export data from A to

B using export data source, empty cube A, create partitionon A, re-import data from B, and delete cube B.



15. How can we perform Data Loading Tuning?

Data Loading Tuning can be performed as follows: Watch the ABAP code in transfer and update rules.Load Balance on different Servers. Indexes on Source Tables.Use fixed length files if the data is loaded from flat files

and put the file on the application server.Use the 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 the data is loaded a lot at

once. Load Master Data before loading Transaction Data.



16. What is a data source?

The source which is sending data to a particular info sourceon BW, for example it contains an OCUSTOMER_ATTRdata source to supply attributes to OCUSTOMER from R/3.

17. What is an info source?

Group of logically related objects, for example theOCUSTOMER info source will contain data related to

customer and attributes like customer number, address,phone no, etc.



18. Difference between display attributes and

navigational attributes?Display attribute is one, which is used only for displaypurpose in the report. Where as navigational attribute isused for drilling down in the report. We don't need to

maintain Navigational attribute in the cube as acharacteristic (that is the advantage) to drill down.



19. Why we delete the setup tables (LBWG) & fill

them (OLI*BW)?Initially we don't delete the setup tables but when we dochange in extract structure we go for it. We r changing theextract structure right, that means there are some newlyadded fields in that which r not before. So to get the

required data (i.e.; the data which is required is taken andto avoid redundancy) we delete n then fill the setuptables.To refresh the statistical data. The extraction set up readsthe dataset that you want to process such as, customersorders with the tables like VBAK, VBAP) & fills the relevantcommunication structure with the data. The data is storedin cluster tables from where it is read when theinitialization is run. It is important that duringinitialization phase, no one generates or modifiesapplication data, at least until the tables can be set up.



20. What types of partitioning are there for BW?

There are two Partitioning Performance aspects for BW(Cube & PSA)

Query Data Retrieval Performance Improvement:

Partitioning by (say) Date Range improves data retrieval bymaking best use of database execution plans and indexes(of say Oracle database engine).

Transactional Load Partitioning Improvement:

Partitioning based on expected load volumes and dataelement sizes. Improves data loading into PSA and Cubesby info packages (Eg. without timeouts).



21. How can compare data in R/3 with data in a

BW Cube after the daily delta loads? When go to R/3 TCode RSA3 and run the extractor. It will give you the number of records extracted. Then go to BW Monitor tocheck the number of records in the PSA and check to see if it isthe same & also in the monitor header tab.

RSA3 is a simple extractor checker program that allows you torule out extracts problems in R/3. It is simple to use, but onlyreally tells you if the extractor works. Since records that getupdated into Cubes/ODS structures are controlled by UpdateRules, you will not be able to determine what is in the Cubecompared to what is in the R/3 environment. You will need tocompare records on a 1:1 basis against records in R/3 transactionsfor the functional area in question. I would recommend enlistingthe help of the end user community to assist since theypresumably know the data.



22. What is Dataflow in BW ?

Data flows from transactional system to analytical system(BW). Data Sources on the transactional system needs tobe replicated on BW side and attached to info Source andupdate rules respectively.



23. Difference between info cube and ODS?

Info cube is structured as star schema (extended) where afact table is surrounded by different dim table that arelinked with DIM'ids. And the data wise, you will haveaggregated data in the cubes. No overwrite functionality

ODS is a flat structure (flat table) with no star schemaconcept and which will have granular data (detailed level).Overwrite functionality.



24. What is landscape of R/3 & what is landscape

of BW ?Then Landscape of R/3 have the development system,testing system, production system

Development system: All the implementation part is donein this sys. (I.e., Analysis of objects developing,

modification etc) and from here the objects are transportedto the testing system, but before transporting an initial testknown as Unit testing (testing of objects) is done in thedevelopment sys.

Testing/Quality system: quality check is done in this

system and integration testing is done.Production system: All the extraction part takes place in

this sys.



25. What is a source system?

The source system is that which sends the data to BW likeR/3, f lat file, oracle database or external systems.



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