User Guide

SAP AG November 2002
See also:
B* Trees for Tables [Page
104]
Table Access Using a B* Tree [Page
107]
Table ID
The database user [Page 136] specifies a table by entering its name. The table is accessed
internally using a table ID of a fixed length.
The relationship between the table name and this table ID is stored in the database catalog
[Page 131].
In addition, SAP DB has a special management structure (file directory), in which the root
pages [Page 103] of B* trees [Page 128] are assigned to table IDs.
The Table IDs are stored in the file directory together with a type flag and other information.
The type flag specifies whether the table contains primary data, secondary key [Page
102] ,
or LONG data. The type flag specification enables one Table ID to be used for all the B* trees
required for the logical structures of one table.
B* Trees for Tables
B* trees [Page 128] are set up for the following kinds of table:
• Tables with primary data
• Tables with secondary keys [Page
102]
• Tables with LONG columns
See also: Table Access [Page
103]
You can find some examples for setting up B* trees here:
• B* Trees for Tables with LONG Columns [Page
104]
• B* Trees for Tables with Secondary Keys [Page
105]
• B* Trees for Tables with LONG Columns and Secondary Keys [Page
106]
B* Trees for Table with LONG Columns
An example of B* trees for tables [Page 104] is a B* tree [Page 128] structure in which the
table has primary data and data of data type LONG.
User Manual: SAP DB 104