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, which makes reorganizations
unnecessary. The data areas can be
extended online.
Structures and algorithms are available that are required for realizing an efficient I/O strategy, and that make reorganizations unnecessary. The data management algorithms have the following characteristics:
· Sort data on SELECT (Table Access (SELECT) using B* Trees)
· Sort data on INSERT (Table Access (INSERT) using B* Trees)
· UPDATE data in place (Table Access (UPDATE) using B* Trees)
· DELETE data in place (Table Access (DELETE) using B* Trees)
For this data management, the database system uses the following logical storage structures:
· Primary tables (with primary keys and secondary keys)
· Secondary key tables (data of the secondary keys)
· B* tree
B* trees are created for the following tables (see B* Trees for Tables): Primary tables and secondary key tables.
For tables
with LONG
columns (data type LONG, also known as BLOBs = Binary Large Objects), a
special data processing procedure takes place by using the B*
trees.