Data Class : The data class defines the physical area of the database in which the table is logically stored.
APPL0 Master data
APPL1 Transaction data
APPL2 Organizational and customizing data
Size Category : The size category value specifies the probable space required for a table in the database.
Buffering : The buffering status specifies whether a table can be buffered or not.
Buffering allowed but switched off
Buffering switched on
This buffering is preferable for large tables where there are frequent single-record accesses (using SELECT SINGLE ...)
Fully buffered : If a read access is made to a record, all records of the table are transferred to the buffer.
This buffering is preferable for comparatively small tables for which the access range is large.Tables best suited to full buffering are small, frequently read, and rarely updated.
Generic Area buffered : When one record of the table is accessed, all the records whose left justified part of the key (generic key area) match this record are loaded . The generic key is a part of the primary key of the table that is left-justified.
The number of key fields to be entered must lie between 1 and the number of key fields -1.
The individual generic areas are treated like independent tables that are fully buffered.
Log data changes : The logging flag defines whether changes to the data records of a table should be logged. If logging is activated, every change (with UPDATE, DELETE) to an existing data record by a user or an application program is recorded in a log table in the database.
The logs can be displayed with Transaction table history - SCU3 .
Write access only with Java : If this indicator is checked , the contents of the table may only be changed from within Java.
- The most commonly used data classes are :
APPL0 Master data
APPL1 Transaction data
APPL2 Organizational and customizing data
- The data class has an effect on table storage only for the database systems ORACLE and INFORMIX.
Size Category : The size category value specifies the probable space required for a table in the database.
- The category value ranges from 0 to 14 with each category having some fixed storage area value in the database.
- When you create a table, initial space is saved for it in the database. If more space is required later as a result of data that has been entered, the storage space is increased in accordance with the category selected.
Buffering : The buffering status specifies whether a table can be buffered or not.
- Buffering a table improves the performance when accessing the data records contained in the table.
- For buffering status we have the following options :
Buffering allowed but switched off
Buffering switched on
- If Buffering is switched on we need to specify the type of buffering :
This buffering is preferable for large tables where there are frequent single-record accesses (using SELECT SINGLE ...)
Fully buffered : If a read access is made to a record, all records of the table are transferred to the buffer.
This buffering is preferable for comparatively small tables for which the access range is large.Tables best suited to full buffering are small, frequently read, and rarely updated.
Generic Area buffered : When one record of the table is accessed, all the records whose left justified part of the key (generic key area) match this record are loaded . The generic key is a part of the primary key of the table that is left-justified.
The number of key fields to be entered must lie between 1 and the number of key fields -1.
The individual generic areas are treated like independent tables that are fully buffered.
Log data changes : The logging flag defines whether changes to the data records of a table should be logged. If logging is activated, every change (with UPDATE, DELETE) to an existing data record by a user or an application program is recorded in a log table in the database.
The logs can be displayed with Transaction table history - SCU3 .
Write access only with Java : If this indicator is checked , the contents of the table may only be changed from within Java.