SAP-BW interview questions part-V

What is ODS?• Operational DataSource is used for detailed storage of data. We can overwrite data in the ODS. The data is stored in transparent tables.

What are BW Statistics and what is its use?
• They are group of Business Content InfoCubes which are used to measure performance for Query and Load Monitoring. It also shows the usage of aggregates, OLAP and Warehouse management.

What are the steps to extract data from R/3?
• Replicate DataSources
• Assign InfoSources
• Maintain Communication Structure and Transfer rules
• Create and InfoPackage
• Load Data

What are the delta options available when you load from flat file?
• The 3 options for Delta Management with Flat Files:
o Full Upload
o New Status for Changed records (ODS Object only)
o Additive Delta (ODS Object & InfoCube)

What are the extractor types?
• Application Specific
o BW Content FI, HR, CO, SAP CRM, LO Cockpit
o Customer-Generated Extractors
LIS, FI-SL, CO-PA
• Cross Application (Generic Extractors)
o DB View, InfoSet, Function Module

What are the steps involved in LO Extraction?
• The steps are:
o RSA5 Select the DataSources
o LBWE Maintain DataSources and Activate Extract Structures
o LBWG Delete Setup Tables
o 0LI*BW Setup tables
o RSA3 Check extraction and the data in Setup tables
o LBWQ Check the extraction queue
o LBWF Log for LO Extract Structures
o RSA7 BW Delta Queue Monitor

How to create a connection with LIS InfoStructures?
• LBW0 Connecting LIS InfoStructures to BW
What is the difference between ODS and InfoCube and MultiProvider?
• ODS: Provides granular data, allows overwrite and data is in transparent tables, ideal for drilldown and RRI.
• CUBE: Follows the star schema, we can only append data, ideal for primary reporting.
• MultiProvider: Does not have physical data. It allows to access data from different InfoProviders (Cube, ODS, InfoObject). It is also preferred for reporting.

What are Start routines, Transfer routines and Update routines?
• Start Routines: The start routine is run for each DataPackage after the data has been written to the PSA and before the transfer rules have been executed. It allows complex computations for a key figure or a characteristic. It has no return value. Its purpose is to execute preliminary calculations and to store them in global DataStructures. This structure or table can be accessed in the other routines. The entire DataPackage in the transfer structure format is used as a parameter for the routine.
• Transfer / Update Routines: They are defined at the InfoObject level. It is like the Start Routine. It is independent of the DataSource. We can use this to define Global Data and Global Checks.

What is the difference between start routine and update routine, when, how and why are they called?
• Start routine can be used to access InfoPackage while update routines are used while updating the Data Targets.

What is Star Schema?
In Star Schema model, Fact table is surrounded by dimensional tables. Fact table is usually very large, that means it contains millions to billions of records. On the other hand dimensional tables are very small. Hence they contain a few thousands to few million records. In practice, Fact table holds transactional data and dimensional table holds master data.
The dimensional tables are specific to a fact table. This means that dimensional tables are not shared to across other fact tables. When other fact table such as a product needs the same product dimension data another dimension table that is specific to a new fact table is needed.
This situation creates data management problems such as master data redundancy because the very same product is duplicated in several dimensional tables instead of sharing from one single master data table. This problem can be solved in extended star schema.

What is slowly changing dimension?
Dimensions those changes with time are called slowly changing dimension.

What is fact table?
Fact table is the collection if facts and relations that means foreign keys with the dimension. Actually fact table holds transactional data.

What is dimension table?
Dimension table is a collection of logically related descriptive attributes that means characteristics.

How many tables does info cube contain?
Actually info cube contains two tables’ E table and F (fact) table.