<P> The key distinctions between HANA and previous generation SAP systems are that it is a column - oriented, in - memory database, that combines OLAP and OLTP operations into a single system . Storing data in main memory rather on disk provides faster data access and, by extension, faster querying and processing . While storing data in - memory confers performance advantages, it is a more costly form data storage . Observing data access patterns, up to 85% of data in an enterprise system may be infrequently accessed therefore it can be cost - effective to store frequently accessed, or "hot", data in - memory while the less frequently accessed "warm" data is stored on disk, an approach SAP have term "Dynamic tiering". </P> <P> Column - oriented systems store all data for a single column in the same location, rather than storing all data for a single row in the same location (row - oriented systems). This can enable performance improvements for OLAP queries on large datasets and allows greater vertical compression of similar types of data in a single column . If the read times for column - stored data is fast enough, consolidated views of the data can be performed on the fly, removing the need for maintaining aggregate views and its associated data redundancy . </P> <P> Although row - oriented systems have traditionally been favored for OLTP, in - memory storage opens techniques to develop hybrid systems suitable for both OLAP and OLTP capabilities, removing the need to maintain separate systems for OLTP and OLAP operations . </P> <P> The index server performs session management, authorization, transaction management and command processing . The database has both a row store and a columnar store . Users can create tables using either store, but the columnar store has more capabilities and is most frequently used . The index server also manages persistence between cached memory images of database objects, log files and permanent storage files . XS engine allows to build web applications . </P>

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