SAP HANA Interview Questions You'll Most Likely Be Asked: Job Interview Questions Series

By Vibrant Publishers

• 270 SAP HANA Interview Questions
• 75 HR Interview Questions
• Real life scenario based questions
• Strategies to respond to interview questions
• Free 2 Aptitude Tests online

SAP HANA Interview Questions You'll Most Likely Be Asked is a perfect companion to stand ahead above the rest in today's competitive job market. Rather than going through comprehensive, textbook-sized reference guides, this book includes only the information required immediately for job search to build an IT career.

The following is included in this book:

• 270 SAP HANA Interview Questions, Answers and proven strategies for getting hired as an IT professional
• Dozens of examples to respond to interview questions
• 75 HR Questions with Answers and proven strategies to give specific, impressive, answers that help nail the interviews
• 2 Aptitude Tests 

About the Series
SAP HANA Interview Questions You'll Most Likely Be Asked is a part of Job Interview Questions Series. As technology now-a-days changes very often, IT Professionals need to be updated with the latest trends in these technologies constantly and more importantly instantly. Job Interview Questions Series is THE answer to this need.

We believe in delivering quality content and do so by tying up with the best authors around the globe. This series of books is written by expert authors and programmers who have been conducting interviews since a decade or more and have gathered vast experiences in the world of information technology. Unlike comprehensive, textbook-sized reference guides, our books include only the required information for job search. Hence, these books are short, concise and ready-to-use by the working professionals.

• Language: English
• Publisher: Vibrant Publishers
• Release date: Jun 9, 2013
• ISBN: 9781946383730

Book preview

General Overview

1: What led to the invention of SAP HANA technology?

Answer:

The following led to the invention of SAP HANA technology:

a) Information explosion where data was growing massively from Gigabytes to Terabytes to Petabytes and business required analytics based on this enormous data

b) Instant data access anytime and anywhere became the customer need to make real time decisions

c) Business required a flexible way to analyze current and historic information for various reporting solutions

2: Which technologies did SAP HANA evolve from?

Answer:

SAP HANA evolved by combining earlier developed technologies, BW Accelerator and Max DB with its in-memory capabilities.

3: What are the main components in SAP HANA?

Answer:

The main components of SAP HANA are:

a) SAP In-Memory Database (IMDB)

b) In-Memory Computing Studio and

c) Data Replication components (SLT, BODS, etc.)

4: What is SAP HANA?

Answer:

SAP HANA is an in-memory technology supported by column-based storage and high data compression that allows processing of massive volumes of data and high speed business reporting. It allows its customers to explore and analyze huge volumes of data from any data source in real time with unprecedented performance. In comparison to traditional RDBMS systems, it is much simpler and faster.

5: What are the capabilities and benefits that HANA offers?

Answer:

a) Real Time data

b) Faster queries on large volumes of data

c) Flexible modeling

d) Minimized data duplication

e) No aggregate tables

6: What are the basic technology concepts in SAP HANA?

Answer:

The basic technology concepts in SAP HANA are:

a) In-Memory where data resides on main memory than on disk

b) Colum based database, Data Compression and Pushing application logic to the database layer

c) Parallel processing and multi-core CPUs leveraging the new hardware technology

7: What is the benefit of In-Memory in SAP HANA?

Answer:

The main benefit of using in-memory database is that accessing data from main memory is much faster than accessing data on disk. A very high-speed bus connects the main memory directly to the processors, whereas in hard disks a chain of buses and controllers are involved.

8: What is columnar storage and how does it support faster access of data?

Answer:

Columnar database stores data in a sequence of columns; the entries of a column get stored in contiguous memory locations. This phenomenon is called columnar storage.

Column store is optimized for READ; only the selected columns will be read during query processing, hence it performs well. It offers significant advantages of data compression or encoding data into fewer bits allowing larger volumes of data in main memory and higher performance in selection and aggregation queries.

9: Are column-based tables always better than row-based tables?

Answer:

No. There are business cases where row based tables are advantageous over column, like in frequently updated databases. If the database is frequently updated or inserted, row-based tables perform faster as they are optimized for write operations.

10: What is the difference between row store and column store?

Answer:

The row store is optimized for WRITE operations and is easy to insert/update. All data has to be read during selection, even if only a few columns are involved in the selection process.

Compared to this, the column store is optimized for performance of READ operations and do not support easy insert/update. After selection, selected rows have to be reconstructed from columns.

11: Can you have row store tables in SAP HANA?

Answer:

HANA can have column or row stores; there is no technical limitation. If you have row-store table in HANA, you cannot create any column views on top of those tables. Typically, Metadata or rarely accessed data is stored in a row-store format.

12: How does insert or update work faster in HANA environment?

Answer:

SAP HANA do not write directly into column store tables while inserting or updating the data as column store is not optimized for write operations. It first writes the data into a row store buffer which is write-optimized and hence faster. It then takes that data, restructures it and pushes it into a column-oriented store. As a final step, it pushes this restructured columnar data into the main column-oriented table. By following this process, SAP HANA makes use of the row store for write operations to ensure faster performance.

13: What degree of data compression is expected in SAP HANA?

Answer:

The degree of data compression depends on the number of unique values in the data; the fewer the unique values, the better the data compression.

14: What is Delta Merge and how does it support faster read operations?

Answer:

Delta merge moves the data from WRITE optimized Delta memory to READ optimized and compressed Main memory. It transforms the data into an optimized format in terms of memory consumption and read performance. By merging the data into the main storage which is column store, read operations would be faster.

15: What are the different ways of performing delta merge operation?

Answer:

Delta Merge can be done automatically by using Smart Merge technology or manually using MERGE DELTA OF function in SQL statement or using right click option in HANA studio.

16: What is memory latency and how does it hit the performance?

Answer:

While executing any application logic on the data, the application has to get the data from the database, process it, and possibly send it back to the database to store the results. Sending data back and forth between the database and the application usually involves communication overhead and is limited by the speed and throughput of the network, this is memory latency.

17: How does SAP HANA handle the latency problem?

Answer:

In SAP HANA, the calculations and application logic are done at the database level thereby eliminating the exchange of intermediate results between the database and the application. This minimizes the communication and data transfer between database and application thereby reducing the overall processing time.

18: How does SAP HANA support parallel processing?

Answer:

SAP HANA leverages the multi-core processors, multi-processor servers and scales out into a distributed landscape to support parallel processing.

19: Which are the top use cases in SAP HANA?

Answer:

The top use cases of SAP HANA are:

a) Real-time Financial Planning

b) Customer Segmentation

c) Genome Analysis

d) Profitability Analysis and

e) Detective HANA

20: What is the difference between SAP BWA and SAP HANA?

Answer:

SAP BWA is only for SAP BW data; its main aim is to accelerate a portion of the BW data which is crucial for business reporting.

SAP HANA is much more than BWA, it replicates data from SAP ECC, BW or any other non-SAP sources. Besides faster reporting, HANA supports flexible modeling and change management.

*****

Architecture

21: What happens when data exceeds the memory size in HANA?

Answer:

In SAP HANA, data is always stored onto disks with a part of database tables being loaded on demand into RAM. It will drop out parts of database tables that were least recently used when the RAM is exhausted. Furthermore, the Smart Data Access data virtualization layer renders data to be accessed transparently in any other database, like Sybase IQ if the data is large.

22: What are the primary prerequisites for SAP BW on HANA?

Answer:

The primary prerequisites for SAP BW on HANA are:

a) Upgrade to SAP Net Weaver 7.02 or above

b) Migrate database (RDBMS) to HANA DB

23: What is the Operating System requirement for SAP HANA?

Answer:

SUSE Linux Enterprise Server

24: Can HANA Server be configured via Scale up or Scale out