1) What is a data class
DATA Class in technical setting in ABAP dictionary is actually defines the physical space in the database (oracle and time space) in which your table actually stored.
You can choose data class while creating tables in ABAP dictionary and your table will automatically stored in to the correct place in database.
There are three mainly used data classes are available in R/3 system:
1) APPL0 (Master Data) : data that is frequently read but rarely updated. an example may be the address book (name address telephone etc..)
2) APPL1 (Transaction Data) : data that is frequently updated. an example may be goods in the ware house which are changed after each purchase order.
3) APPL2 (Organisational data / customization data) : these are the data stored when system are initialized and then rarely changed. like in table with the country codes.
there are USR and USR1 data classes which are reserved for user developments. You can create your own data class (not recommended though) under USR and USR1.
2) What is Size Category
we use size category to define the expected space for the table in the database.
Size category determines the probable space requirement for your table in the database. you can select the storage category from 0 to 4, each storage category have specified fixed storage area in the database. total size category are 0 to 8.
while creating table in the data base an initial space is assigned to the table. later if more space is required due to the data stored in the table.
3) Buffering status
buffering status specifies whether or not table will be buffered.
Buffering not allowed
Buffering allowed but not activated - buffering type is only a suggestion
Buffering allowed - buffering type mandatory
Single record buffering:
Only records of table that are really accessed are buffered. useful when we have a large table data and we frequently used SELECT SINGLE to this table.
Generic Buffering:
When a record of the table is accessed all the record in the table having this field in the generic key fields are loaded in the buffer.
Full buffering:
The system buffer all the records of the table when one record of the table is accessed.
4) Log save data changes : logs of the table can be viewed through through SCU3 transaction.
5) Enhancement category :
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work area : data but only 1 record at a time.
master data: Frequently used but data which not frequently updated.
Transactional data/business data : frequently used and frequently updated.
SAP data management sales order:
TCODE : VA01 - Sales order creation. VA02 VA03.
Tables : VBAK - header table for sales order (sales document header data)
VBAP - Sales order line data
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Package: package is a kind of grouping.
Delivery class: A,C.L,O,E,S,W
Accessed by functional consultant.
Key fields : Primary Index generated automatically with primary key.
Secondary index: SAP sort the data and store it in the buffer called index. we should try to limit the number of the secondary indexes.
Foreign key check : check table key field of one table is field in other table.
Currency/quantity field:
Data Element : Semantic meaning.
Domain : technical attributes fro data element. (CHAR10 ex)
The data class defines the physical area of the database (for ORACLE the TABLESPACE) in which your table is logically stored. If you choose a data class correctly, your table will automatically be assigned to the correct area when it is created on the database.
The most important data classes are (other than the system data):
APPL2 Organizational and customizing data
Master data is data which is frequently read, but rarely updated. Transaction data is data which is frequently updated. Organizational und customizing data is data which is defined when the system is initialized and then rarely changed.
There are two more data classes available, USR and USR2. These are reserved for user developments. The tables assigned to these data classes are stored in a tablespace for user developments.
Note:The data class only has an effect on table storage for the database systems ORACLE and INFORMIX.
The size category determines the probable space requirement for a table in the database.
You can select the categories 0 to 4 for your table. Each category is assigned a specific 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.
Press F4 on the field Size category to see the number of data records that can be maintained for the individual categories of your table without complications ensuing. These complications could be for example a reorganization becoming necessary because the maximum space to be reserved for the table was exceeded due to the maintained size category.
This depends on how the table is used, for example on the expected volume of data in the table or on the type of access to a table. (mainly read or mainly write access to the table. In the latter case, for example, one would not select buffering).
You should therefore select
- Buffering not allowed if a table may not be buffered.
- Buffering allowed but not activated if buffering is principally allowed for a table, but at the moment no buffering should be active. The buffering type specified in this case is only a suggestion.
- Buffering allowed if the table should be buffered. In this case a buffering type must be specified.
Single record buff
Generic area buffered
full data
Append Structure:
Include Structure:
Transparent table : one to one relationship between the key fields and other fields of table. the against one key field there will be only one entry in the table.
Table Cluster (cluster table): one to many relation ship. Against the one key field there may be many entries in the table. key fields of the cluster tables must be same. (or at least few starting key fields on which we define a cluster table.)
Several logical data records from different cluster tables can be stored together in one physical record in a table cluster.
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Number of the continuation record
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Length of the string in Vardata
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Contains the entries from the data fields of the assigned cluster tables as a string. The maximum length n depends on the database system used.
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A table pool corresponds to a table in the database in which all records from the pooled tables assigned to the table pool are stored.
The definition of a pool consists of two key fields (Tabname and Varkey) and a long argument field (Vardata). A pool has the following structure:
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Contains the entries from all key fields of the pooled table record as a string. The maximum length for n is 110.
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Length of the string in Vardata
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Contains the entries from all data fields of the pooled table record as a string. The maximum length n depends on the database system used.
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- one step maintenance : only one screen.
- two step maintenance : one screen for entry data and other for display data.
Lock Objects : ??????????
Currency and quantity fields : always when we declare these fields in our SE11 table we must add a reference to another standard SAP table.
Search Help : ????????????
Include and append structure:
Append structures can only be added to one table.
if a table/structure with append structure is copied , fields of the append structure will become field of the target table.
Includes are used to group fields, an include structure can be assigned to many tables. If you add a fields to an include structure, all tables/structures, which contain that include structure, will be updated too.
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