topic Re: DDIC Questions in Application Development and Automation Discussions

DDIC Questions

Former Member — Wed, 18 Apr 2007 10:54:41 GMT

Hai

>>> What is exact meaning of SIZE CATEGORY and DATA CLASS?

>>> What Is generic means of DOMAIN and DATA ELEMENT?

>>> What generic meaning of FOREIGN key relationship ?

>>> What is INdex? What is Buffering?

Thanks with regards

Re: DDIC Questions

Former Member — Wed, 18 Apr 2007 10:59:10 GMT

hi,

size category: here we specify the initial size of the db i.e. approx how many records it will hold.

domain: it contains the techinal attributes of the field like the datatype, size of the field.

data elemnt: it contains the documentation of the field like descr.

foreign key relationship: if a primary key of a table is used as the primary key in another DB then these tables have a foreigh key relationship.

regards,

Navneeth.K

Re: DDIC Questions

Former Member — Wed, 18 Apr 2007 11:01:13 GMT

2. What Is generic means of DOMAIN and DATA ELEMENT?

Domain will define the technical properties of a field. It means it descibes that the field is of which type like char, int etc with the length.

Dataelement is used to call the refer to the field which has given in a table into other fields, so that all the technical properties which are defined for a field will be copied to that field.

3. What generic meaning of FOREIGN key relationship ?

It means the field which is having foreign key relationship with any other field in the same or other table, then the data which you enter in this field is dependent on the foreign key field which you have defined in the other table. It means the records which r there for foreign key field for those records only you can further entries in the child table.

Regards

Haritha.

Re: DDIC Questions

Former Member — Wed, 18 Apr 2007 11:01:40 GMT

Hi,

What is exact meaning of SIZE CATEGORY and DATA CLASS?

Size category one of technical settings of a table which will tell how many records are going to be in that table based on this correct size in the memory is allocated.

Data class means which type of data (master,Application) are you going to store in that table.

What Is generic means of DOMAIN and DATA ELEMENT?

Domain gives the technical attributes of a field like DATA Type and LENGTH

Data element gives the technical description of the field that has to be displayed

What generic meaning of FOREIGN key relationship ?

It is the relationship with other tables for this field. It will give the dependencies of that field in other tables.

What is INdex? What is Buffering?

Index is the search criteria that is used to search the records from the table when we write select statement.

There will be different types of buffering.

Generally we don't allow buffering for the tables we create.

reward if useful

regards,

ANJI

Re: DDIC Questions

Former Member — Wed, 18 Apr 2007 11:03:04 GMT

domain gives the techincal attributes of the data object.

( techincal attributes - data type , length , decimal places, uppercase or lowercase etc...)

data element gives the descriptional attributes of the data object.

( descriptional attributes - The business functionality of the object )

Using foreign keys, you can easily create value checks for input fields. Foreign keys can also be used to link several tables in a view or a lock object

index:

An index is a database object that can be defined for an individual column or a series of columns in a database table.You can create an index (also called a secondary key) to make it quicker to find data records in a table.

buffering:

With generic buffering, all the records in the buffer whose generic key fields match this record are loaded when one record of the table is accessed.

The table buffer is located between the application and the database. Its goal is to cache portions of a database table in the application server to reduce database load and network communication.for more details:

http://help.sap.com/saphelp_nw04/helpdata/en/f7/e4c5a8a84a11d194eb00a0c929b3c3/content.htm

regards,

madhu

Re: DDIC Questions

Former Member — Wed, 18 Apr 2007 11:05:18 GMT

A foreign key is a field in a table that is connected to another table via a foreign key relationship. The purpose of the foreign key relationship is to validate the data being entered into one table by checking against a valid set of values in another table. The table that contains the foreign key is called the foreign key table. The table that contains the valid set of values is called the check table (see Figure 4.1). The field that is validated and on which the foreign key relationship is created is called the foreign key.

The data class determines the tablespace in which a table is created. The database administrator uses tablespaces to organize and maintain the database. Choosing the proper tablespace makes database administration easier, increases system performance, and to some extent even increases system availability because the database is usually taken offline for reorganizations.

The size category determines the size of the initial extent and next extents, as well as the number of possible next extents. Choosing too low a number will cause one or more additional extents to be allocated. A table that spans multiple extents decreases system performance, increases database maintenance, and lowers system availability, again because the database is usually taken offline for reorganizations.

Buffering increases system performance by caching data locally on the application server. When done properly, fewer database accesses are required because the data that is most often read is stored in RAM on the application server. Good candidates for buffering are tables that are seldom updated and often read.

Activating the automatic logging feature on a table will cause a change document to be created each time the table is changed. This feature slows table updates, and so is only used for tables containing critical data. For non-critical tables, change document objects should be used.

praveen

Re: DDIC Questions

Former Member — Wed, 18 Apr 2007 11:12:24 GMT

Hi,

1)Size-Category

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

<u>Data element</u>

A data element is an elementary type. It describes the type attributes

(data type, field length and possibly the number of decimal places) and

screen information (explanatory text or field help) about unstructured

data objects (table fields and structure fields or variables).

Table fields and structure fields with the same contents should refer to

the same data element. This ensures that the attributes of these fields

are always consistent.

A data element can be referenced in ABAP programs with TYPE. This

permits you to define variables that take on the type attributes of the

data element in an ABAP program.

<u>Domain</u>

Domain name

A domain describes the technical attributes of a field, such as the data

type or the number of positions in a field. The domain defines primarily

a value range describing the valid data values for the fields referring

to this domain.

Different technical fields of the same type can be combined in a domain.

Fields referring to the same domain are changed at the same time when a

domain is changed. This ensures the consistency of these fields.

3)Foreign key

A foreign key creates a link between two tables T1 and T2. Every primary

key field from T1 (check table) is assigned a field from table T2

(foreign key field). The fields from T2 assigned to primary key fields

are marked as foreign key fields.

The most important function of the foreign key is the support of data

integrity. The foreign key fields can only accept values which appear in

the primary key of the check table. During input the values of the

foreign key fields can thus be checked against the entries of the

assigned key fields of the check table.

Foreign keys are also the foundation for defining lock objects,

maintenance views and help views. These objects contain fields from

several tables. All the tables used in such an object must be linked

with foreign keys.

You can search a table for data records that satisfy certain search criteria faster using an index

with regards,

Jay