HANA is many things. It is an own, in-memory database manager with columnar store by SAP AG. Including a number of newly-developed components for ERP, advanced planning, Business Intelligence, Analytics, etcetera.

What is special about SAP HANA’s database management system? First, a general introduction.

Increasing processor power and larger memory have become available at lower prices over the past years. Operating system software is capable of dealing efficiently with these new capabilities. This makes the concept of performing data intensive tasks in memory increasingly attractive: in-memory computing.

For the in-memory operations, the fastest memory available should preferably be used. A cache on the processor is preferred over the separate RAM. And preferably, the fastest of the caches is used. The fastest cache is usually the smallest, so the use of the different types of memory requires careful consideration for each calculation task.

Another aspect is the component that performs data-intensive calculations. Close to the data it needs to be done, preferably. By the database management software itself. That makes sense but is not in line with the traditional roles of application servers and database servers, in which they exchange a lot of data. Moving the calculation to the database server is called code pushdown.

When calculation tasks on large data sets are performed in-memory, on the database server, it is key that the source data can be requested in an efficient way. For this, it is usually more efficient to request a single table column in its entirety.

The relational model for databases is row oriented, and this is how traditional database management software works. To be able to request a table column, we need a column store. This is a way of storing data so that we have efficient access to parts of the column, or even the full column. Even when it contains millions of items.

A column store increases the efficiency of certain calculations on large data sets considerably. But a large part of the tasks of the database manager will still be row oriented.

This is a key challenge of the design of database management software: on large data sets it has to work well for both row and column oriented operations. An ERP-application requests many, simple, row oriented read and write operations: request a row, update and store it. An analytics-application requests fewer operations, mostly reading, but on larger data sets.

Simplified: the traditional row oriented organization of data is well-suited for Online Transactional Processing (OLTP, like ERP). The column store suits Online Analytical Processing (OLAP, like business intelligence) much better.

Following: how does the column store of SAP HANA work?