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SAP HANA interview questions

SAP HANA Scheduling using Windows Scheduler And HDBSQL:
HDBSQL the command line interface helps SAP HANA system interact with SAP HANA database. As SAP HANA adds new features, it si important to note that SAP HANA has a scheduler missing now. This prevents us from scheduling routine batch jobs at DB level.However, it is possible to schedule at windows level using OS scheduler and SAP HANA HDBSQL command-line tool
If an user wants to work with SAP HANA DB he needs a user accoutn with a set of privileges to work on SAP HANADB
What is a role?
Role is the set of privileges
Why is a role important in SAP HANA DB?
Every user who gets created and works with SAP HANA DB will be grnated a role which internally carries set of privileges
This is a clear demarcation of level of access a user gets and actions a user can perform at SAP HANA DB
What happens when SAP HANA DB is installed?
As a part of default SAP HANA installation some standard user like SYSTEM which is the user account used for day-to-day activities gets created. SYSTEM user account is also important as this is account that created DB users and offer them privilege to perform tasks at SAP HANA DB level
In addition to standard SYSTEM users, some DB technical accounts that perform database technicalities like statistics collection, SYs operation are also created. Some of these accounts include SYS, _SYS_STATISTICS. Note that we cannot log onto SAP HANA DB using these accounts

SAP HANA Operating System User Overview
Users who wish o work with SAP HANA DB need a user account at DB level. During SAP HANA install SYSTEM account the DB account gets created that helps in other user account creation and administration
At OS level an user account adm called the OS system administrator gets created. This account controls SAP HANA system files and file structures at OS level. This user doesnt exist at DB. In short this is system administrator account from OS context
What is significance of OS admin form SAP HANA studio perspective?
This user credentials are neede dto perform DB start/stop, recovery of DB and such DB admin tasks from sAP HANA studio interface. The first step (i.e) to start a SAP HANA system requires adm OS administrator credentials
SAP HANA Backup File Location:
As with any system SAP HANA system needs to be backed up. The backup destination of SAP HANA is smae as common software system $DIR_INSTANCE/backup/data
This is default backup destination and it is possible to change the backup destination using global.ini parameter basepath_databackup
It is also possible to make changes using SAP HANA studio configuration tab. Choose file global.ini->persistence, make changes
SAP HANA Project Orange:
On November 7th, 2011 SAP released its much awaited in-memory database originally names as Project Orange but later rebranded as SAP HANA. Hence both names represent same. As per SAP project orange is huge and it is  a project that will likely replace all the vendor databases including oracle, sql server , db2 and migrate entire SAP infrastructure onto its DB
It is good practice to always work on latest version of SAP HANA studio. We can check for updates manually on a regular basis.We cna also configure SAP HANA studio to check for updates automatically
We can configure automated updates download form site (same as simple microsoft updates)

How to specify the update site details?
In SAP HANA studio specify the update site details using following navigation
Window->Preferences->Install/Update->Available Software Sites
Choose Add option and specify name of update repository and its location there

SAP HANA studio manual updates:
It is possible to apply manual updates as follows :
From Main menu choose, Help->Check For Updates — Teh SAP HANA studio software checks specified site for latest updates
If you see an update look at the instructions, follow instruction and install updates

SAP HANA Studio Manual And Automated Updates – SAP HANA Studio automated updates :
We cna configure SAP HANA studio to check for updates automatically and get an alert on new update if one exists
From Main menu choose -> windows->Preferences->Install/Update->Automatic Updates
Specify update settings to get automated update availability alert
SAP Offers ERP Migration From DB to HANA:
Recently SAP announced that business suite is in ramp-up for HANA. ERP migration (i.e) BW migration from current RDBMS database to HANA is going to be risk free as per SAP
SAP recommends a dual delivery setup wherein we first migrateERP RDBMS to HANA, test the migrated systems, verify migration, move end users to BW on HANA system
SAP HANA migration is a full database migration and hence all the users in current RDBMS of BW will be migrated to SAP HANA
All users/roles in BW application are initially defined using ERP application layer. Hence after migration there will be a simple role change for users of SAP HANA datamodeling studio in HANA datamart
HDBSQL is the command line interface that can be used to query information on DB and DB objects. This cna be used in interactive, non-interactive mode. Following are some common options that come with HDBSQL
-i – This is DB instance ID. it is usally possible to make use of windows services panel to get to know detials on DB instance
-u – This is useraccoutn using which we try to log into DB. Note that user account must exist at DB
-p – This is password for DB user
-U – this is credential from user store
-z – This sets autocommit mode off
-saml-assertion – Used file to provide SAML assertion
-r – This option supresses usage of prepared statements
-n – this is hostname of machine on which DB is installed and port number
SAP HANA Analytics Foundation For SAP Business Suite:
SPA HANA analytics foundation for SAP Business suite popularly called SHAF was released on December 2012
It provides infrastructure to enable data from SAP business suite to be used by SAP HANA for analytic processing
This provides views in SAP HANA for reporting on data that persisted in SAP HANA table format from SAP business suite of products without any data transfer form original tables in suite
This helps business users analyze data and make business decisions.
Technical implemnetation is using SAP HANA integrated studio that makes reporting possible from SAP business suite
To put it simple SHAF is the reporting tool to generate business report from SAP business suite of products
SAP HANA system Properties Brief Overview:
In any system its properties are usually stored in a common file called as configuration file. Say in case of oracle DB it is init.ora (or) spfile.ora
In case of a PHP system it si php.ini
similar to that SAP HANA system stores its configuration properties in a system file. The properties of SAP HANA system are defined as part of different configuration parameters in this file
Parameters of same category are bundled and categorized in this configuration file

How can we change the properties of SAP HANA system?
As with all other systems, an user wiht administrative privilege INIFILE ADMIN will be able to make changes to the properties in the file
1) In SAP HANA studio administration editor, choose Configuration tab – This gives us list of all configuration files
2) Choos eand expand the particular configuraiton file we want to change – This lists all the sections of that particular configuration file
3) Expand the section of interest – Choose parameter we wish to change. By default these parameters will have some value set in place
4) Choose Change in context menu of configuraiton parameter. This pops Change Configuration Value dialog box
5) Enter new value
6) While entering new value if these changes are confined to specific hosts, we need to choose the Hosts area of Change Configuration value dialog box, choose specific hosts and enter host specific values
Thus it is possible to change value and have its scope across systems,hosts. If specified hosts specific value takes precedence over systemwide value

Some parameters can’t be changed at host level and they show disabled icon in Hosts area of Change Configuraiton value dialog

Does the change in parameter value require system restart?
simple answer is No. If needed relevant components of system are restarted on it own
SAP HANA System Schema:
System schema are database schemas that get created in SAP HANA database. As these are not realtime users we cannot make use of these accounts to log into database
Following is the list of SAP HANA System schema
2) _SYS_BIC – This contains details on column views, metadata
4) _SYS_REPO – This is repsitory owner
5) _SYS_STATISTICS – Schema used for statistics collection at DB. Performance of a system depends on statistics and it needs to be uptodate for optimal system performance
SAP HANA Studio An Introduction Usage Overview:
SAP HANA studio is a java application that is supported on top of eclipse platform. It is a all in one tool that is being used by administrators, developers, project managers as it ahs lots of features to be used by many different people in an organization
1) SAP HANA studio tool has provision to start, stop, monitor the system, perform configuration, create modeled views, stored procedures etc
2) It connects to SAP HANA DB using sql (JDBC internally)
3) SAP HANA DB acts as repository to store modeled views, stored procedures and such artifacts

Who can make use of SAP HANA studio?
Based on its features and functionality it cna be used by range of personnel in an organization including

1) SAP HANA Admins
2) DBA’s
3) Dat aModeler
4) SAP HANA Developer
5) Lifecycle managers (usually ALM personnel)
SAP HANA has some technical database users that usually cant be used for logging into database. Instead they support various technicalities of SAP HANA database. One such user is _SYS_STATISTICS, _SYS_REPO etc.
_SYS_REPO is teh SAP HANA technical database user that is used by SAP HANA repository.
SAP HANA repository consists of design time versions of many different objects such as analytic views,calculation views, procedures, analytic privileges, roles. The owner of all objects in repository and activated runtime version is _SYS_REPO user
How is query analysed in SAP HANA database?
Query analysis in any database starts with query plan. SAP HANA DB is no different.We can generate explain plan for query under investigation in SQL console and use this to determine next steps
Enter the query in SLQ console and in context menu choose EXPLAIN PLAN. this is for explain plan for single query.To generate multiple explain plans for many different queries we enter many SQL’s seperated by semicolon
EXPLAIN PLAN is displayed in Result tab
Are plan explanations stored at DB level?
Yes, SQL EXPLAIn PLAN explanations are stored at explain_plan_table view of SYS schema. This cna be used for later examination
Just as the case with all software systems SAP HANA comes with its own flavour of command line execution using HDBSQL.We can execute sql commands, DB procedures, query information on DB and DB objects using HDBSQL component of SAP HANA software. We can access databases on both local systems and remote computers
How do I start using HDBSQL?
Execute hdbsql [options] to call hdbsql
Note that hdbsql cna be used in both interactive and non-interactive mode to query informaiton on DB and DB objects
We can also import command from a file and execute it in backend using HDBSQL
This is a common terminology usd among SAP datawarehousing professionals these days. It is simple SAP BW netweaver datawarehouse that is hosted and runs on in-memory appliance software SAP HANA. SAP supports migration of existing BW RDBMS to SAP HANAand it provider faster output than regular dataabses like ORacle,SQL Server
It is possible to migrate data from existingERP (SAP BW) to SAP HANA using dual delivery model. Themigration is a full DB migration and involves some changes in SAP HANA datamart roles after migration
SAP BW on HANA Sizing :
It is important to have capacity planning of SAP BW on SAP HANA and sizing involves following considerations
1) RAM Sizing – Get details on full data footprint – This involves memory sizing for column store data , memory sizing for row store data, memory sizing for runtime objects, data load, query execution
2) CPU sizing
3) Disk Sizing

Capacity planning involves personnel who will be working on this technical infrastructure. We can also make use of an ABAP script that helps us get sizign details
The sizing report /SDF/HANA_BW_SIZING is a easy to deploy script that considers user defined future growth and has many parametrs and is independent of source databasecompression
SAP HANA Database Backup Methods & Tools :
It is possible to perform SAP HANA database backup using different tools and methods

1) SAP HANA studio – This eclipse framework offers a way to perform SAP HANA backup. This requires OS <sid>adm privilege to proceed further without any issues
2) SQL commands
3) Batch mode – This is set of commands in a file run usually as batch script