Persistence layer is used in case of system failure, database corruption or power failure to restore the database to most recent save point in HANA. Persistence Layer is responsible for data and transaction log backup and also to store configuration of HANA system.Backup of data and transaction log files are taken as per Backup settings in HANA system configuration. It can be set to minutes, Hours and days and destination of backup is also defined under Backup settings.When a backup is run for data and transaction files, system takes the backup from all the servers in HANA system.Persistence Layer is ... Read More

It consists of various components as mentioned above for processing of SQL statements from application users hosted on the top of HANA system.User requests via user interface/web browsers are sent to Web server hosting application which is communicated to SQL/MDX Processor in form of SQL queries. These are further segregated to different data engines in Index server according to query types.Session and Transaction Manager authorize SQL transactions and keep track of all the transactions either completed or running in the system.

In SAP HANA system, Session and Transaction Manager is responsible to keep track of all the executed transactions in HANA database. It includes both running transactions and closed transaction. When a transaction in HANA system is failed due to any reason, Transaction Manager informs corresponding engine to handle the error.Session Manager is responsible to manage open and closed sessions and to authorize all the transactions executed in HANA db.

It will use both OLAP and Join engine. The join between the FACT and DIM will be executed in the OLAP engine and joins inside the attribute views will be executed in the JOIN engine so both the engines will be used.

In SAP HANA system, there are three basic engines used to processes queries in SAP HANA. Following engines are used −Join EngineOLAP EngineCalculation EngineJoin EngineUsed when querying an Attribute View in SAP HANAOLAP EngineAnalytic Views (without derived columns) use the OLAP EngineCalculation EngineCalculation Views or Analytic Views with derived columns use this engine

SQL/MDX processor in HANA system processes all SQL and MDX statements executed in HANA system. SQL statements are generated for all the tables, schemas and MDX statements are raised for OLAP data processing. SQL stands for Structured Query Language and is Relational database language to manage two dimensional objects in HANA db.MDX stands for Multi Dimension Expression and is an OLAP language for processing MDX statements for multidimensional models.SQL/MDX Processor directs all the statement to relevant engines for processing and Engine optimization. It is used for authorization management in executing queries and Error handling while processing SQL/MDX statements.Following functions are ... Read More

Index Server is heart of SAP HANA system and is responsible for processing all SQL statements sent to HANA database. This server contains SQL/MDX Processing engine that is responsible to process and analyze data in HANA db.Index Server also contains Persistence layer for scalability and restoration of the system. In case of system failure, power failure or database corruption, Persistence layer is responsible for the restoration of HANA system to last save point.When you are running complex and large calculations, and there is a system failure Persistence layer is used to ensure that transactions are either fully executed or complete ... Read More

Each HANA system contains multiple serves inside, which are responsible to perform different functions. Index Server is heart of SAP HANA system which contains SQL/MDX processor for handling SQL statements. Key component includes −Index ServerPreprocessorName ServerStatistics ServerHANA XS EngineSAP Host AgentSAP Solution Manager Diagnostic AgentSAP HANA Studio + RepositorySAP HANA Software Update Manager SUM

You can use following SQL statement for this −CREATE VIRTUAL TABLE ExampleCREATE VIRTUAL TABLE ABC.test_VT AT “ORCL_11G_WIN”.”NULL”.”OUTLN”.”Dept”;In this SQL statement, ABC.test_VT is Virtual table name“ORCL_11G_WIN”.”NULL”.”OUTLN”.”Dept”;- Remote location for creating Virtual table

When a remote source is added, you can see all the existing tables under that data source in HANA Studio. Next is to create virtual table mapping to data in the remote data sources in SAP HANA Studio. This can be done using GUI option.To add a table as a virtual table, you need to navigate to remote data source → Schema name → Table name → Right-click and Add as Virtual TableBelow shows how you can add a table as a Virtual Table using HANA Studio.