SAP HANA MODELLING Interview Questions and Answers

Q1: Which non-SAP system can SAP HANA connect?

Ans: Oracle Enterprise, IBM Informix.

Q2: What are the Views available in the Quick launch of Information modeler?

Ans: Navigator, Where-used list, Job log, Properties.

Q3: For what Life cycle management perspective is used?

Ans: We use Life cycle management perspective to Upgrade/Updates for HANA studio.

Q4: OPD for data replication API is used in which replication?

Ans: Data services 4.0.

Q5:  How can you ensure that data is consistent in source system and HANA system?

Ans: Since any changes in the source system are tracked in dedicated logging tables, the replication status for each changed data record is transparent. An entry of logging table is deleted after a successful commit statement from HANA database and this procedure ensures the data consistency between a source system and HANA system.

Q6:  Which section controls the data processing in the HANA DB?

Ans: Transaction Manager controls the data processing in the HANA DB.

Q7: What is the component present in Persistence layer in the HANA DB?

Ans: The component present in Persistence layer in the HANA DB is Page management & Logger.

Q8: What are the types of joins are possible in Attribute view?

Ans:

1. Referential join
2. Inner join
3. Outer join

Q9: What is the role of Persistence Layer?

Ans: It ensures that the database is restored to the most recent committed state after a restart and that transactions are either completely executed or completely undone. The persistence layer offers interfaces for writing and reading data. It also contains SAP HANA ‘s logger that manages the transaction lo.  Log entries can be written implicitly by the persistence layer when data is written via the persistence interface or explicitly by using a log interface.

Q:10 What does HANA DB performs During power outage?

Ans: Recovers log between last data savepoint & time of failure.

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Q11: What is the Operating System of IMDB ?

Ans: SUSE Linux Enterprise Server

Q:12 Which is the default perspective of IMCE Studio?

Ans: Administrator console

Q:13 Name the editions of SAP HANA Software?

Ans:

1. Platform edition
2. Enterprise edition
3. Enterprise extended edition.

Q14: What are the benefits of implementing SAP HANA with SAP ERP?

Ans:

1. Performance optimization for operational reporting
2. Processing of large volumes of data
3. Provision of real-time analytics.

Q15: Do we need a special driver to access data within HANA?

Ans:  HANA provides both a 32-bit and 64-bit ODBC and JDBC drivers. SAP BusinessObjects 4.0, Data Services 4.0 and many other SAP based tools have built-in support for these drivers to help support all the features  HANA has to offer.

Q16: How can we load data in HANA and how to access the data stored in HANA?

Ans:

Loading data:  There are several options available to get data into HANA. SAP provides a real-time replication server called SLT Replication. With this server you can replicate data from a SAP system or non-SAP RDMS systems into HANA. The data is copied in its native format and will then need to be de-normalized on HANA using information views ( attribute views, analytic views and calculation views). According to the documentation, you can also leverage the Sybase Replication Server for log based replication. In addition, Data Services 4.0 can be used to move data into HANA and can update data at near real time if needed.  Data Services 4.0 can also de-normalize the data given its abundance of data transforms and provide data quality and cleansing transforms that will help clean the data before it is loaded into HANA.

Access the data:  There are several ways to access the data within HANA. The ideal way to access data is through SAP BusinessObjects 4.0. There are multiple tools within the BusinessObjects 4.0 platform for accessing HANA data. You can utilize Web Intelligence, Crystal Reports, Explorer, “Analysis Edition for Microsoft Office”, Mobile and Dashboard (Xcelsius). In short, any tool in the platform that supports ODBC or a Universe can be utilized to access data within HANA. These options work for SAP BW (powered by HANA) or for HANA (Standalone). If you have SAP BW powered by HANA, you can utilize any of the traditional query tools. For those that like viewing raw data results, you can utilize HANA Studios to execute SQL statements and view the results.

Q17: Why we need to go for going In-memory?

Ans: One reason is the number of CPU cycles per second is increasing and the cost of processors is decreasing. For managing the data in memory, there is five-minute rule which is based on the suggestion that it costs more to wait for the data to be fetched from disk than it costs to keep data in memory so it depends on how often you fetch the data.

For example, there is a table and no matter how large it is and this table is touched by a query at least once every 55 minutes, it is less expensive (in hardware costs) to keep it in memory than to read it from memory and if it is frequently accessed it is less expensive to store it in memory.

Q:18 What are the advantages of Column based tables and Row-based tables?

Ans:

Advantages of Column based tables:

1. Calculations are typically executed on single or a few columns only.
2. The table is searched based on values of a few columns.
3. The table has a large number of columns.
4. The table has a large number of rows and columnar operations are required (aggregate, scan, etc.).
5. High compression rates can be achieved because the majority of the columns contain only a few distinct values (compared to a number of rows).

Advantages of Row-based tables:

1. The application needs to only process a single record at one time (many selects and/or updates of single records).
2. The application typically needs to access a complete record (or row).
3. The columns contain mainly distinct values so that the compression rate would be low.
4. Neither aggregations nor fast searching is required.
5. The table has a small number of rows (e. g. configuration tables).

Q19: What is Derived Attribute Views?

Ans: In some business cases, it is required to use the same attribute view more than once

In such cases, one can derive an attribute view using the base view which acts as reference to the base attribute view. The derived attribute view will be opened in the read-only mode. The only editable field will be its description. The derived attribute view will act as a reference to its base attribute view