topic Re: cluster table in Application Development and Automation Discussions

cluster table

Former Member — Thu, 07 Feb 2008 06:51:14 GMT

What is the difference between Cluser table and a view and what are the operations that can be done on a cluster table ??

Re: cluster table

Former Member — Thu, 07 Feb 2008 06:55:21 GMT

A table pool or table cluster should be used exclusively for storing internal control information (screen sequences, program parameters, temporary data, continuous texts such as documentation). Data of commercial relevance is usually stored in transparent tables.

Several logical data records from different cluster tables can be stored together in one physical record in a table cluster.

A cluster key consists of a series of freely definable key fields and a field (Pageno) for distinguishing continuation records. A cluster also contains a long field (Vardata) that contains the contents of the data fields of the cluster tables for this key. If the data does not fit into the long field, continuation records are created. Control information on the structure of the data string is still written at the beginning of the Vardata field.

The records of all cluster tables with the same key are stored under one key in the assigned table cluster. The values of the key fields are stored in the corresponding key fields of the table cluster. The values of all data fields of the assigned cluster tables are written as a string to the Vardata field of the table cluster. Besides the actual data values, the data string contains information on the structure of the data and which table it comes from. If the string exceeds the maximum length of the Vardata field, a continuation record is written with the same key values. The continuation records for a key are distinguished by their value in field Pageno. The actual length of the string in the Vardata field is stored in the Pagelg field by the database interface.

You need the structural information stored in the ABAP Dictionary to read the data from a pooled table or cluster table correctly. These tables can therefore only be processed using Open SQL with the cluster interface, and not with Native SQL directly in the database.

http://help.sap.com/saphelp_nw04/helpdata/en/cf/21f083446011d189700000e8322d00/content.htm

Regards,

Re: cluster table

Vijay — Thu, 07 Feb 2008 06:55:36 GMT

The followings are different types of views:

Database View (SE11)

Database views are implement an inner join, that is, only records of the primary table (selected via the join operation) for which the corresponding records of the secondary tables also exist are fetched. Inconsistencies between primary and secondary table could, therefore, lead to a reduced selection set.

In database views, the join conditions can be formulated using equality relationships between any base fields. In the other types of view, they must be taken from existing foreign keys. That is, tables can only be collected in a maintenance or help view if they are linked to one another via foreign keys.

Help View ( SE54)

Help views are used to output additional information when the online help system is called.

When the F4 button is pressed for a screen field, a check is first made on whether a matchcode is defined for this field. If this is not the case, the help view is displayed in which the check table of the field is the primary table. Thus, for each table no more than one help view can be created, that is, a table can only be primary table in at most one help view.

Projection View

Projection views are used to suppress or mask certain fields in a table (projection), thus minimizing the number of interfaces. This means that only the data that is actually required is exchanged when the database is accessed.

A projection view can draw upon only one table. Selection conditions cannot be specified for projection views.

Maintenance View ( SE54 )

Maintenance views enable a business-oriented approach to looking at data, while at the same time, making it possible to maintain the data involved. Data from several tables can be summarized in a maintenance view and maintained collectively via this view. That is, the data is entered via the view and then distributed to the underlying tables by the system.

Please have a look at below link. It will help you.

http://help.sap.com/saphelp_nw04/helpdata/en/cf/21ed06446011d189700000e8322d00/frameset.htm

for more detailed info look on:

http://www.sap-img.com/abap/what-is-the-different-types-and-usage-of-views.htm

https://www.sdn.sap.com/irj/sdn/wiki?path=/display/home/abap+dictionary&;

cluster table

Several logical data records from different cluster tables can be stored together in one physical record in a table cluster.

regards

vijay

reward points if helpful

Re: cluster table

Former Member — Thu, 07 Feb 2008 06:57:56 GMT

Table pools (pools) and table clusters (clusters) are special table types in the ABAP Dictionary. The data from several different tables can be stored together in a table pool or table cluster. Tables assigned to a table pool or table cluster are referred to as pooled tables or cluster tables.A table pool or table cluster should be used exclusively for storing internal control information (screen sequences, program parameters, temporary data, continuous texts such as documentation). All data of commercial relevance is stored exclusively in transparent tables.

Several logical data records from different cluster tables can be stored together in one physical record in a table cluster. A table cluster has the following structure:

Field Data type Meaning

CLKEY1 * First key field

CLKEY2 * Second key field

... ... ...

CLKEYn * nth key field

Pageno INT2(5) Number of the continuation record

Timestamp CHAR(14) Time stamps

Pagelg INT2(5) Length of the string in Vardata

Vardata RAW (n) Contains the entries from the data fields of the assigned cluster tables as a string, max. length n depends on the database system used

VIEWS

Data about an application object is often distributed on several tables. By defining a view, you can define an application-dependent view that combines this data. The structure of such a view is defined by specifying the tables and fields used in the view. Fields that are not required can be hidden, thereby minimizing interfaces. A view can be used in ABAP programs for data selection.

The data of a view is derived from one or more tables, but not stored physically. The base tables of the view must be selected in the first step of a view definition. In the second step, these tables must be linked by defining the join conditions. It is also possible to use the join condition from a foreign key defined between the tables .In the third step, you must select the fields of the base tables to be used in the view. Selection conditions that restrict the records in the view can be formulated in the fourth step.

Four different view types are supported :

· Database views are implemented with an equivalent view on the database.

· Projection views are used to hide fields of a table (only projection).

· Help views can be used as selection method in search helps.

· Maintenance views permit you to maintain the data distributed on several tables for one application object at one time.

PLZ REWARD IF USEFUL

VIVEK