What is SAP HANA ?

The term SAP HANA is used for both (in-memory) database and an application platform. SAP HANA was a platform offered as both an appliance and a cloud service.
SAP HANA in-memory database is a specialized database with following features

• All the read & write operations, take place in memory.
• Data can be stored both in row and column format.
• Every column is a secondary index and there is no need to maintain separate indexes.
• It has a much better Data compression as data from the same column can be stored together
• It utilizes distributive, multiprocessing & massive parallel processing capabilities of modern CPUs.

It comes with a tightly integrated lightweight application server out-of-the-box, SAP HANA XS or Extended Application Services. SAP HANA XS is designed/engineered specifically for the SAP HANA database and is closely integrated with it to take care of

• validation logic
• control flow logic
• service enablement logic
• as most of
• calculation logic
• data-intensive processing
• are pushed down into the database layers to leverage the power of the features mentioned above.

HANA Extended Application Services uses server-side JavaScript as the main programming language supports REST-based OData services with both JSON and Atom XML rendering using which complex transnational business applications can be build.

Data-intensive logic can be written in SQL and SQL Script and it also has built-in support for XML for Analysis (XMLA) and Multidimensional Expression language (MDX) access for analytics.
The above information is just to get started. I would keep updating this blog with more up-to-date information.