How data stored in cluster table

[Former Member]

How data stored in cluster table

[Former Member]

How data stored in cluster table

[anversha_s]

hi,

Cluster tables contain continuous text, for example, documentation.

Several cluster tables can be combined to form a table cluster.

Several logical lines of different tables are combined to form a physical record in this table type.

This permits object-by-object storage or object-by-object access.

In order to combine tables in clusters, at least parts of the keys must agree.

Several cluster tables are stored in one corresponding table on the database.

Rgds

Anver

[Former Member]

Go to transaction ABAPDOCU and press the CNTRL + F8. Enter the text CLUSTER TABLE and press enter. Now you can read about it's usage and storage.

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.

[Former Member]

Hi

A table Cluster is a collection of many (10 to hundred ) of small tables that

are meant to have few records .

A row in the table Cluster is read it fetches data from the matching row of all

the component tables . Reading a row of table cluster can be understood like ,

a view of the matching entries (max one row from each) from the component tables.

One common requirement is that all the component tables must have a part of their primary key as common , this helps in referencing data from each component tables .

You might create a table cluster if you need to create hundreds of small tables that each hold only a few rows of data. To implement these small tables as cluster tables, you first create the definition of a table cluster in R/3 to hold them all. When activated, an associated single table (the table cluster ) will be created in the database. You can then define cluster tables within R/3 and assign them all to your table cluster .

Eg . the system configuration data is stored in several tables and it is referenced every time the system information is required (i e at logon) .

Here , the data from different tables is picked and consolidated to give an overall

picture of the system information.

Regards

Pankaj

[Former Member]

Hi,

- Cluster tables combine the data from several tables with identical (or almost identical) keys into one physical record on the database.

- Data is written to a database in compressed form.

- Retrieval of data is very fast if the primary key is known.

- Cluster tables are defined in the data dictionary as transparent tables.

- External programs can NOT interpret the data in a cluster table.

- Special language elements EXPORT TO DATABASE, IMPORT TO DATABASE and DELETE FROM DATABASE are used to process data in the cluster tables.

Hope this will help.

Regards,

Ferry Lianto