Databases Reference
In-Depth Information
A column-based RDBMS will store each column together, as shown as follows:
1,2,3
Joe,Emma,Sam
Smith,Thomson,Wiggins
35000,40000,42500
EUR,USD,USD
A column-based database will be able to more quickly scan a column of data than a row-based
system. This point is especially important for data reporting (like SAP BW), and enables results
to be given to the user much more quickly.
Another important aspect of a column-based RDBMS is data compression. Since all values in a
column are stored together, there is the possibility of storing the value only once, alongside the
number of occurrences. So in the example table we've just seen, the last column might be stored
as follows:
EUR, 2:USD
This might not seem important, but in a table that contains several million lines, the space
savings are potentially huge. SAP indicates that data can be compressed to between 10
percent and 25 percent of its original size. Of course, this means less data to scan through for
the system—and since data is in memory, it means more data—between 4 and 10 times—can
be kept in memory at once.
The full list of different strong points and weaknesses of column-based versus row-based
database systems is beyond the scope of this topic. Several interesting comparisons exist,
and a good page to start would be the Wikipedia page concerning column-based RDBMSs,
whose URL is given in the
People and places you should get to know
section.
In this section we've taken a look at the business need behind the SAP HANA product, the
history of the software SAP HANA inherits from, the basic system architecture that makes
up the product, as well as a fast overview of the column-based database concept.
In the next section, we'll take a look at what you need to get SAP HANA Studio up and running
on your computer, so that you can start developing your first SAP HANA application.
