Index Server

As we discussed, Index Server is the heart of SAP HANA database system and plays a vital role of containing actual data and engines for processing that data. The Index Server takes care of all these requests and processing triggered by the firing of SQL or MDX in the system and processes them successfully, the entire HANA processing accomplishments takes place in Index Server.

Data Engines

Index Server has exclusive data engines to handle and processes the SQL/MDX statements that are fired into the HANA database system. It also maintains the durability of HANA system with the help of persistence layer and ensures HANA system is restored to most recent state when there is a restart of system failure. Session and Transaction Manager are also considered as the parts of Index Server which help the management of transactions in the Sap HANA System.

The Architecture of Index Server

SQL/MDX Processor

This component inside the Index Server is responsible for processing various SQL/MDX transactions alongside data engines responsible for running those queries. All query requests are segmented by this preprocessor thereby directing them to correct engine for the performance Optimization.

It also ensures that all SQL/MDX requests are authorized and also provide error handling for efficient processing of these statements. It contains several engines and processors for query execution −

SQL Processor:

Once the SQL queries are fired to the SAP HANA System, the incoming SQL requests are received by an exclusive processor called SQL Processor. Data manipulation statements are executed by the SQL Processor itself.

Other types of requests are delegated to other components. Data definition statements are dispatched to the Metadata Manager, transaction control statements are forwarded to the Transaction Manager, planning commands are routed to the Planning Engine and procedure calls are forwarded to the stored procedure processor.

SQLScript:

The SAP HANA database has its own scripting language named SQLScript that is designed to enable optimizations and parallelization. SQLScript is a collection of extensions to SQL.

SQLScript is based on side-effect free functions that operate on tables using SQL queries for set processing. The motivation for SQLScript is to offload data-intensive application logic into the database.

Multidimensional Expressions (MDX):

MDX is a language for querying and manipulating the multidimensional data stored in OLAP cubes.

Incoming MDX requests are processed by the MDX engine and also forwarded to the Calc Engine.

MDX (Multi Dimension Expression) is query language for OLAP systems like SQL is used for the Relational database. MDX Engine is responsible for handling queries and manipulates multidimensional data stored in OLAP cubes.

Planning Engine is responsible for running planning operations within SAP HANA database.

Calculation Engine converts data into Calculation models to create logical execution plan to support parallel processing of statements.

Stored Procedure processor executes procedure calls for optimized processing; it converts OLAP cubes to HANA optimized cubes.