User Guide

SAP AG November 2002
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Data Management Using B* Trees
The SAP DB data management architecture ensures efficient data storage on disks and fast
data access. The SAP DB database system performs automatic load balancing, thereby
making reorganization unnecessary. The data areas [Page
131] can be extended online.
The developers of SAP DB have ensured that the structures required by users to implement
an efficient I/O strategy are provided and that reorganization does not need to be carried out
at all. For this reason, a special data management for the logical data pages has been
created. This data management includes the following features:
• Sort data on SELECT(Table Access (SELECT) Using B* Trees [Page
107])
• Sort data on INSERT(Table Access (INSERT) Using B* Trees [Page
109])
• UPDATE data in place (Table Access (UPDATE) Using B* Trees [Page
111])
• DELETE data in place (Table Access (DELETE) Using B* Trees [Page
110])
In addition to this special data management, the database system uses the following logical
storage structures:
• Primary tables (with primary keys [Page
101] and secondary keys [Page 102])
• Secondary key tables (data of the secondary keys)
• B* Tree [Page
128]
There are build B* trees for the following tables (B* Trees for Tables [Page 104]): primary
tables and secondary key tables
For tables with LONG columns (data type LONG also known as binary large objects
(BLOBs)) there is a special data processing using B* trees for tables with LONG columns.
Concepts
Primary Key [Page 101]
Secondary Key [Page
102]
B* Tree [Page
128]
Table ID [Page 104]
Primary Key
Each SAP DB table has a primary key. The primary key is either defined by the database user
[Page 136] or generated internally. A user-defined primary key can consist of multiple
columns.
User Manual: SAP DB 101