SAP HANA Interview
Questions You'll Most Likely Be Asked is a perfect companion to stand ahead
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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 download available on (link unavailable)
SAP HANA Interview Questions You'll Most Likely Be Asked is part of the Job Interview Questions Series. As technology changes often, IT professionals need to be updated with the latest trends constantly and more importantly, instantly. The Job Interview Questions Series is the answer to this need.
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Samples Questions and Answers
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 grew massively from gigabytes to terabytes to petabytes, and
businesses required analytics based on this enormous data.
b) Instant data
access anytime and anywhere became a customer need to make real-time decisions.
c) Businesses 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
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 in main memory rather than on disk.
b) Column-based
database, data compression, and pushing application logic to the database
layer.
c) Parallel processing
and multi-core CPUs leveraging new hardware technology.
7. What is the benefit of In-Memory in SAP HANA?
Answer:
The main benefit
of using an 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:
A 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-based tables,
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 does 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 a 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 does 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
the MERGE DELTA OF function in an SQL statement or using the 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, which 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
the database and application, thereby reducing the overall processing time.
| Overall, "SAP HANA Interview Questions You'll Most Likely Be Asked" is a useful resource for SAP HANA consultants who want to prepare for job interviews and stay informed about the latest trends and developments in the field. By studying the questions and answers provided in the book, consultants can gain the knowledge and confidence they need to succeed in their careers. |  |
