Databases Reference
In-Depth Information
The software
The database software powering SAP HANA is what's known as a column-based RDBMS, and is
a logical evolution of the following three existing technologies that were already in use at SAP:
Ê
TREX
: SAP's search engine, a component of SAP NetWeaver since 2000. TREX already
included in-memory and columnar store attributes, which were designed to improve
performance by searching data already in main memory, and already in highly
optimized data structures.
Ê
MaxDB
: SAP's own RDBMS technology. MaxDB is a very capable, relatively simple
(when compared to some other big players such as Oracle) RDBMS system. It is capable
of running the SAP ERP or SAP BW, despite having very low system requirements and a
fairly shallow learning curve. MaxDB brought in the persistence (that is, what happens
when the power goes off—a crucial question for an in-memory system) and backup
layers to SAP HANA.
Ê
P*Time
: A lightweight, OLTP in-memory RDBMS system, acquired by SAP in 2005
when they bought Transact in Memory. P*Time provided the in-memory backbone
to the SAP HANA software. It is worth noting that P*Time is a traditional row-based,
not column-based, data store.
By combining these three proven technologies, SAP has managed to produce a coherent,
persistent in-memory database system, known internally as
NewDB
(which says a lot about
how the technology is viewed from inside SAP!).
How does a column-based database work?
In any given database, tables such as the following table exist:
Employee
Firstname
Lastname
Salary Currency
1
Joe
Smith
35000 EUR
2
Emma
Thomson 40000 USD
3
Sam
Wiggins 42500 USD
Whereas, a traditional database system will store the data in a row-based format, as shown
as follows:
1,Joe,Smith,35000,EUR
2,Emma,Thomson,40000,USD
3,Sam,Wiggins,42500,USD
