Do checkout this commonly asked SAP BW HANA Interview Q/A Series and prepare for your interviews easily. This is Part 9 of 10 Part Series.
SAP BW HANA Interview Series
1. What do you understand by Data Replication in SAP BW HANA?
Ans: When you copy the data from any SAP or Non SAP Source System to SAP HANA Database, then it is known as SAP Data Replication in BW HANA. Replication technique in SAP BW HANA supports both real time & near real time data integration, makes it easy for reporting & analysis.
Multiple data sources can be replicated, which includes DSs from SAP ERP System, SAP ECC System, Flat files, Non SAP Systems etc. Replication is one of the important process as it makes data available immediately by avoiding latency & this period could be done periodically or regularly, based on the business requirement or the type of data.
2. How the delta mechanism work in SAP BW HANA from SAP ECC ?
Ans: Delta mechanism in SAP Business Warehouse is one of the most important aspect of Data Acquisition in SAP BW HANA. This mechanisms enables that only the new records which got added recently or the records which are changed in the source system, can only be extracted from the source system.
This is a good way to save the time it take to load the compete set of data. Instead only new or changed data get loaded to SAP BW from SAP ECC and thus time got saved and performance got optimized.
We can give the delta type as (init or delta) in the DTP we create. Init is to initialize the delta for the first time and delta is to bring the delta records. The status of the deltas in SAP BWHANA could be either seen in RSA7 or ODQMON depending upon the BW version.
3. Why we use Star Schema & Extended Star Schema in SAP BW HANA ?
Ans: STAR Schema and Extended STAR Schema, both are the data modelling approaches in SAP BW HANA.
Structure wise they both are a bit different. Star schema is having one fact table surrounded by many dimension tables, making it simple for querying & reporting on the data. Whereas in extended start schema structure, the concept of line item was introduced. Huge amount of granular data is being represented at the line item level and this extended star schema is a very good option for huge amount of transactional data.
Both these schemas provide flexibility in data analysis and modelling by optimizing query performance & supporting real time data availability.
4. How do you manage historical data in SAP BW HANA?
Ans : There is a concept called as Data Aging. Through this mechanism, large amount of historical data is being managed and stored. This way we are able to separate the old data with the new frequently used data. Old & less frequently data is being stored in secondary storage areas.
Hot data or frequently used data remains in the main memory whereas cold / warm data moves to the lower storage areas.
5. Is Data Archiving & Data Aging same?
Ans: No, Data archiving and data aging both are different mechanism. Data archiving is done when we want to remove the data entirely from the system and it is not available in future whereas data aging is the one, where the data is just moved to the lower storage layers in SAP Storage. Though, the data will be there and will be used as and when required.
With archiving, the database got reduce and the storage cost also reduced. Data aging helps in query performance optimization
Hope you like the SAP BW HANA Interviews Series Part 9.
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