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Clients connect to the database system which forms a session within the database in the form of SQL statements. In the HANA database, each SQL statement is processed in the context of a transaction. New sessions are assigned to a new transaction.
Traditional database applications uses JDBC and ODBC interface to communicate with the database management system over a network connection and application uses SQL to manage and query the data stored in the database. In the HANA database Index server is the main component of database management which contains the actual data stores and the engines for processing the data. The index server processes incoming SQL or MDX statements in the context of transaction.
The Transaction manager coordinates database transactions, and keeps track of running and closed transactions. When a transaction is committed or rolled back, the transaction manager informs the involved storage engines about this event so they can execute necessary actions.
The HANA database has its own scripting language called SQLScript that is designed to enable optimization and parallelization. HANA supports the Business Functional Library (BFL) and Predictive Analysis Library (PAL) and can be called directly from within SQLScript. It also supports the development of programs written in R language.
SQL and SQLScript are implemented using a common infrastructure of Built-in functions. That have access to various meta definitions such as definitions of relational tables, columns, views, and indexes, definitions of SQLScript procedures. This Metadata is stored in one common catalog (row store or column store).
The Persistence layer ensures that the database after
a restart is restored to the most recent committed state. It uses a combination
of write-ahead logs, shadow paging and save points. The persistence layer
also contains Logger that manages the transaction log.
The Index server uses the Preprocessor Server for analyzing the text data and extracting the information based on text search capabilities. The Name Server knows where the components are running and which data is located on which server. The Statistics Server collects information about status, performance and resource consumption from other servers in the system.
