B* Tree 

All SAP DB data is stored in structures called B* trees. The B* tree method is far more efficient for accessing the rows of a table than other access methods (for example, sequential scans).

A B* tree spans several levels from the root level at the top, to the index levels, through to the lowest leaf level (one root level, n index levels (n>=1), one leaf level).

The storage units are called pages or data pages. SAP DB Version 7 supports a page size of 8 KB.

In SAP DB Version 7, all subsequent comparisons in a B* tree use ASCII code (each character is assigned a numerical value between 0 and 255). The comparisons are performed for all values on a character-by-character basis.

The sort criterion for building a B* tree is the primary key.

B* Tree

See also:

Root/Index Page

Leaf Page

Table Access

B* Trees for Tables