SAP HANA Interview Questions and Answers
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Mention what is SAP HANA?
SAP HANA stands for High Performance Analytical Appliance- in-memory computing engine. HANA is linked to ERP systems; Frontend modeling studio can be used for replication server management and load control.
What is the development language used by SAP HANA?
Development language used by SAP HANA is C++
Name the operating system SAP HANA supports.
More than 70% of customers run their SAP workloads on Linux with the use of SUSE Linux Enterprise Server, which is the best OS choice for SAP HANA.
Does HANA/IMDB replace Oracle?
Once the business suite keeps running on IMDB, Oracle won’t be required any more by SAP clients who purchase HANA. This doesn’t affect anything in the short term because those people buying HANA today will still need an Oracle ERP system.
Mention the two types of Relational Data stored in HANA?
The two types of relational data stored in HANA includes
Explain the column and Row store in HANA?
HANA supports both type of data store in database. Row store is used when you need to use Select statement and no aggregations are performed.
Column store is used to perform aggregations and HANA Modeling is supported only on Column based tables.
Mention what is the role of the persistence layer in SAP HANA?
SAP HANA has an in-memory computing engine and access the data straightaway without any backup. To avoid the risk of losing data in case of hardware failure or power cutoff, persistence layer comes as a savior and stores all the data in the hard drive which is not volatile.
Explain Parallel Processing in SAP HANA?
Using the columnar data storage approach, the workload in SAP HANA is divided vertically. The columnar approach allows linear searching and aggregation of data rather than two-dimensional data structure. If more than one column is to be processed, each task is assigned to diverse processor. Operations on one column are then collimated by column divisions processed by different processors.
What is the operating system supported by SAP HANA?
Currently SUSE Linux enterprise server X86-64 (SLES) 11 SP1 is the operating system supported by SAP HANA.
Which companies are providing SAP HANA hardware appliances?
There are total 11 vendors for SAP HANA hardware appliances. Most common are:
What is the use of SAP HANA studio?
HANA studio is an eclipsed based tool and provides support for development and administration in HANA system. You can perform HANA Modeling on the top of tables in database, Data provisioning, HANA Administration and various other activities using HANA studio.
SAP HANA Studio client is available for Windows XP, Windows Vista, and Windows 7 for 32 bit and 64 bit operating system.
What does HANA cost?
SAP hasn’t completely affirmed HANA permitting costs yet the equipment is some place around $1-200k for every TB. Add to this permitting costs which are as yet being made on a for every client premise.
Mention what is modeling studio?
- Modeling studio in HANA performs multiple tasks like,
- Declares which tables are stored in HANA, first part is to get the meta-data and then schedule data replication jobs.
- Manage Data Services to enter the data from SAP Business Warehouse and other systems.
- Manage ERP instances connection, the current release does not support connecting to several ERP instances.
- Use data services for the modeling.
- Do modeling in HANA itself.
- Essential licenses for SAP BO data services.
What are the different license keys type in HANA system? What is their validity?
- Temporary License key
- Permanent License Key
Temporary License keys are automatically installed when you install the HANA database. These keys are valid only for 90 days and you should request permanent license keys from SAP market place before expiry of this 90 days period after installation.
Permanent License keys are valid till the predefine expiration date. License keys specify amount of memory licensed to target HANA installation.
What do you understand by SAP HANA In-Memory Computing Engine IMCE?
In-Memory concept of SAP HANA means that all the data is stored in RAM memory. A conventional database transfer data from memory in 5 milliseconds however SAP HANA In-memory takes 5 nanoseconds to read data.
SAP HANA uses multicore CPU architecture and stores data in row and column based storage in HANA database.
Which operating system is supported by HANA system?
Only operating system that is supported by HANA is Suse Linux Enterprise Server SP1/SP2 (SLES SP1/2).
Mention what are the different compression techniques?
There are three different compression techniques
- Run-length encoding
- Cluster encoding
- Dictionary encoding
Mention what is latency?
Latency is referred to the length of time to replicate data from the source system to the target system.
Explain what is transformation rules?
Transformation rule is the rule specified in the advanced replication setting transaction for the source table such that data is transformed during the replication process.
What is the functional difference between Row and Column based storage? Where do we use Row based storage and column based storage?
Consider below table- FCTSales
Row Based Storage:
- Samsung Note 6
- Lenovo A110
Column Based Storage
- Samsung Note6
- Lenovo A110
- Where to use Row based storage?
- Select * from FCTSales where Country=’US’
- Where to use Column based storage?
- Select SUM (Units_sold) from FCTSales where Product=’Lenovo A110’
Explain how you can avoid un-necessary information from being stored?
To avoid un-necessary information from being stored, you have to pause the replication by stopping the schema-related jobs.
Mention what is the role of master controller job in SAP HANA?
The job is arranged on demand and is responsible for
- Creating database triggers and logging table into the source system
- Creating Synonyms
- Writing new entries in admin tables in SLT server when a table is replicated/loaded
Explain what happens if the replication is suspended for a longer period of time or system outage of SLT or HANA system?
If the replication is suspended for a longer period of time, the size of the logging tables increases.
What are the different components in SAP HANA Architecture? What is the use of Index server?
- Index server
- Name server
- Statistical server
- Preprocessor server
- XS Engine
- SAP host Agent
- LM structure
- SAP solution manager diagnostic agent
Index server contains engine to process data in HANA database. These data engines are responsible to handle all SQL/MDX statement in HANA system. Index server also contains Session and Transaction Manager which is responsible to manage all running and completed transactions.
What is the use of Persistence layer in SAP HANA system?
Persistence layer provides inbuilt mechanism for disaster recovery in HANA system. It ensures that database is restored to most recent state in case of a system failure.
Persistence layer also manages data, transaction and configuration logs and backup of these files. A backup of data and log files are performed at save points and is normally scheduled every 5-10 minutes.
Mention what is the role of the transaction manager and session?
The transaction manager co-ordinates database transactions and keeps a record of running and closed transactions. When transaction is rolled back or committed, the transaction manager notifies the involved storage engines about the event so they can run necessary actions.
Explain how SQL statement is processed?
In HANA database each SQL statement is implemented in the reference of the transaction. New session is allotted to a new transaction.
Name various components of SAP HANA?
- SAP HANA DB
- SAP HANA STUDIO
- SAP HANA APPLIANCE
- SAP HANA APPLICATION CLOUD
What are the different types of permanent license keys in HANA system?
There are two types of permanent License keys for HANA system:
Unenforced: If unenforced license key is installed and consumption of HANA system exceeds the license amount of memory, operation of SAP HANA is not affected in this case.
Enforced: If Enforced license key is installed and consumption of HANA system exceeds the license amount of memory, HANA system gets locked. If this situation occurs, HANA system has to be restarted or a new license key should be requested and installed.
In SAP HANA Studio, what is use of different folders when you add a HANA system to Studio?
It is used to perform for backup and recovery in SAP HANA system. You can check backup configuration details, run manual backup, to check last successful back performed, etc. for data and log backup.
This contains RDBMS objects like schemas, tables, views, procedures, etc. You can open SQL editor and design database objects.
This is used to maintain design time repository
You can create new packages and design Information views in HANA system. Various views can be created under content tab to meet business requirement and to perform analytical reports on the top of the Modeling views.
This is used for Smart data access to connect to other databases like HADOOP, TERADATA and SYBASE.
This is used to define users and to assign roles. You can define various privileges on different users using Security tab. You can assign Database and Package privileges to different users to control the data access.
What is the difference between Open Data Preview and Open Definition?
Open Data Preview
This is used to see the data stored in an object- table or a modeling view. When you open data preview, you get three options:
This is used to see the structure of the table − column name, column data type, keys, etc.
What is a new calculated column in a HANA modeling view?
New calculated column is defined as a column added on the fly in Analysis tab when a view is activated. This column doesn’t exist at database level or in Data Foundation or Star Join level.
Why materialized aggregates are not required in HANA?
Since the SAP HANA database resides entirely in-memory all the time, additional complex calculations, functions and data-intensive operations can happen on the data directly in the database. Hence materialized aggregations are not required.
It also provides benefits like
Simplified data model
Higher level of concurrency
Simplified application logic
What is ad hoc analysis?
In traditional data warehouses, such as SAP BW, a lot of pre-aggregation is done for quick results. That is the administrator (IT department) decides which information might be needed for analysis and prepares the result for the end users. This results in fast performance but the end user does not have flexibility.
The performance reduces dramatically if the user wants to do analysis on some data that is not already pre-aggregated. With SAP HANA and its speedy engine, no pre-aggregation is required. The user can perform any kind of operations in their reports and does not have to wait hours to get the data ready for analysis.
How you can connect SAP HANA to Microsoft Excel?
MDX Provider is used to connect MS Excel to SAP HANA database system. It provides driver to connect HANA system to Excel and is further used for data modeling. You can use Microsoft Office Excel 2010/2013 for connectivity with HANA for both 32 bit and 64 bit Windows.
How you can limit the size of data backup files in HANA system?
This can be done in File Based data backup settings. In Backup tab, go to Configuration → Limit Maximum file Size check box and enter the file size.
What are different recovery mechanism can be performed in HANA system?
Most Recent State: Used for recovering the database to the time as close as possible to the current time. For this recovery the data backup and log backup have to be available since last data backup and log area are required to perform the above type recovery.
Point in Time: Used for recovering the database to the specific point in time. For this recovery the data backup and log backup have to be available since last data backup and log area are required to perform the above type recovery.
Specific Data Backup: Used for recovering the database to a specified data backup. Specific data backup is required for the above type of recovery option.
Specific Log Position: This recovery type is an advanced option that can be used in exceptional cases where a previous recovery failed.
How to manage HANA users step by step?
A user has to be assigned the necessary privileges in order to work with SAP HANA database. Predefined privileges are available and ready to be granted to specific users such as Operation-users, Monitoring-User, backup-user.
What is Configuration and Monitoring Dashboard?
It is an application that runs on SLT replication server to specify configuration information (such as source system, target system, and relevant connections) so that data can be replicated. It can also use it to monitor the replication status (transaction LTR).
Status Yellow: It may occur due to triggers which are not yet created successfully.
Status Red: It may occur if master job is aborted (manually in transaction SM37).
What is the best way to manage, operate, and monitor SAP HANA systems?
SAP HANA is a young database with interesting features of SAP HANA. First of all SAP HANA is a in-memory database. It is accessible for administration via various channels. Directly from the Server, It is not the most convenient method but you can use HDBSQL to manage databases. With the web based interface HANA cockpit you can browse and manage SAP HANA environments. The Client HANA Studio is the most complete tool to administer SAP HANA but it has to be physically installed and therefore is dependent of the client hardware.
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