1.What are the differences between a OLAP and OLTP applications
d.Lot of historical data
OLTP Detailed Read write Optimized for data applications Not much old data
2.What is a star schema? A fact table at the center and surrounded (linked) by dimension tables
3.What is a slowly changing dimension? A dimension containing a characteristics which changes over a time; for example take employee job title; this changes over a period of time with different job titles
- What are the advantages of Extended star schema of BW vs. the star schema a. use of generated keys (numeric) for faster access b. external hierarchy c. multi language support d. master data common to all cubes e. slowly changing dimensions supported f.aggregates in its own tables for faster access
5.What is the namespace for BW? All SAP objects start with 0 and customer is A-Z; all tables begin with /BIO for SAP and /BIC for customers; All generated objects start with 1-8 (like export data source); prefix 9A is used in APO.
6.What is an info object? Business object like customer, product, etc; they are divided into characteristics and key figures; characteristics are evaluation objects like customer and key figures are measurable objects like sales quantity, etc; characteristics also include special objects like unit and time.
- What are the data types supported by characteristics? NUMC, CHAR (up to 60), DATS and TIMS
8.What is an external hierarchy? Presentation hierarchies are stored in its own tables (hierarchy tables) for characteristic values
9.What are time dependent text / attribute of characteristics? If the text (for example a name of the product /person over time) or if the attribute changes over time (for example job title) then these must be marked as time dependent.
Can you create your own time characteristics? No
What are the types of attributes? Display only and navigational; display only attributes are only for display and no analysis can be done; navigational attributes behave like regular characteristics; for example assume that we have a customer characteristics with country as a navigational attribute; you can analyze the data using customer and country.
What is Alpha conversion? Alpha conversion is used to store data consistently by storing any numeric values with prefixing with Os; for example if you defined material as 6 Numc then number 1 is stored as 000001 but displayed as 1; this removes inconsistencies between 01 vs. 001.
What is the alpha check execution program? This is used to check consistency for BW 2.x before upgrading the system to 3.x; the transaction is RSMDCNVEXIT
What is the attributes only flag? If the flag is set, no master data is stored; this is only used as attribute for other haracteristics; for example comments on a AR document.
15.What is compounding? This defines the superior info object which must be combined to define an object; for example when you define cost center then controlling area is the compounding (superior) object.
16.What is the Bex options for characteristics like F4 help for query definition and execution? This defines how the data is displayed in query definition screen or when query is executed; options are from the data displayed, from master data table (all data) and from dimension data; for example let us assume that you have 100 products in all, 10 products in a cube; in bex you display the query for 2 products; the following options for product will display different data a. selective data only - will display 2 products b. dimension data - will display 10 products c. from master data - will display all 100 products 17. What are the data types allowed for key figures? Amount, number, integer, date and time.
what is the difference between amount/quantity and number - amount/quantity always comes with units; for example sales will be amount and inventory quantity.
What are the aggregation options for key figures? If you are defining prices then you may want to set "no aggregation" or you can define max, min, sum; you can also define exception aggregation like first, last, etc; this is helpful in getting headcount; for example if you define a monthly inventory count key figure you want the count as of last day of the month.
What is the maximum number of key figures you can have in an info cube? 233
What is the maximum number of characteristics you can have per dimension? 248
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