Specification of SAP Tables in the ABAP Dictionary
Purpose
As soon as you create a database table for the SAP System, you can influence its storage parameters by maintaining its technical configuration in the
ABAP dictionary. This technical configuration is used to optimize the space requirements and access response of individual tables.
For more information, see
Creating Tables.
Process Flow
We recommend you to always maintain at least the parameters
Data Class and Size Category in the technical configuration for each table:
The data class logically defines the tablespace where your table is stored. When you select the correct logical table type, your table is automatically assigned to the correct database area when it is created. The F1 help for data class provides information on how to select the proper value for the table.
Data class is assigned to tablespace (for data) using the TAORA table. Data class is assigned to tablespace (for indexes) using the IAORA table.
The size category specifies the estimated space requirements of the table on the database using the categories 0 to 4. When you create a table an INITIAL extent is reserved in the database. If you need more space later, storage space is added corresponding to the selected category (NEXT extent). The F4 help on size category displays the number of data records that will fit in the assigned storage area of the database for each of the categories. A maximum of 300 extents ought to be enough for storing table contents, assuming a database block size of 8 KB.
Size category is assigned to extent size using an entry in the table DD09L and an analysis of the TGORA table for tables or IGORA for indexes. See also Default Value for NEXT. These values of the ABAP Dictionary only represent starting values. For further database operations, use the options provided by SAPDBA for automatically adapting the size of the NEXT extent for all tables. For example, see sapdba -next <tablespace(s)>.
If the table is defined logically, you have to create it in the database in a second step. To do this, use the database storage parameters.