Diff b/n CUSTOM/ POOL tables

[Former Member]

Hi friends,

1) wat are the differences between POOLED and CLUSTER tables?

2) AS per my knowledge POOLED and CLUSTER tables store SYSTEM DATA, Is there any difference in storing the DATA? wat DATA they BOTH individually STORE?

thanks in advance...

ajay kumar...

[Former Member]

i am new to abap but i think the difference b/w pool table and cluster table is:

pool table:

These are logical tables, which must be assigned to a table pool when they are defined. Pooled tables can be used to store control data (such as screen sequences or program parameters).

cluster table:

A table cluster combines several logical tables in the ABAP/4 Dictionary. Several logical rows from different cluster tables are brought together in a single physical record. The records from the cluster tables assigned to a cluster are thus stored in a single common table in the database.

if im incorrect do tell me.

thanks

jawad

[amit_khare]

Check the link -

Regards,

Amit

Reward all helpful replies.

[Former Member]

Hi,

<b>Pooled Tables :</b>

Different tables which are not linked to each other with a common key can be combined into a Table Pool. The tables contained within this pool are called Pooled Tables. A table pool is stored in the database a simple table. The table's data sets contain, in separate fields, the actual key for the data set to be stored, the name of the pooled table and the contents of the data set to be stored.

Using this schema, several logical tables are combined into a single real database table. Although the data structure of each set is lost during the write to the table pool, it is restored during the read by the ABAP/4 Data Dictionary. The ABAP/4 Data Dictionary utilizes its meta-data to accomplish this.

Since information must be prepared (defined) within the ABAP/4 Data Dictionary when it is read or written to (or accessed), this process itself defines these as not transparent tables.

<b>Cluster Tables :</b>

Occasionally, several tables may be linked by a common key. The ABAP/4 Data Dictionary can also combine these tables into a single table. Each data set of the real table within the database contains a key and in a single data field, several data sets of the subsequent table for this key.

As mentioned above, these table types require special data handling, therefore they are not transparent tables.

Note: Both Pooled and Cluster Tables are stored as tables within the database. Only the structures of the two table types which represent a single logical view of the data are defined within the ABAP/4 Data Dictionary. The data is actually stored in bulk storage in a different structure. These tables are commonly loaded into memory (i.e., 'buffered') due to the fact they are typically used for storing internal control information and other types of data with little or no external (business) relevance.

[hymavathi_oruganti]

transparant table will have one to one correspondence with the underlying database

pooled tables wiil be stored in a table pool in the underlying database.

the table pool contains the pooled tables with all rows.

cluster tables will be stored in a table cluster in the undelying database.

the table cluster contains some rows from each table cluster.

[Former Member]

Hi,

Transparent Table:

Exists with the same structure both in dictionary as well as in database exactly with the same data and fields.

Pooled Table:

Pooled tables are logical tables that must be assigned to a table pool when they are defined.

Pooled tables are used to store control data. Several pooled tables can be cominied in a table pool.

The data of these pooled tables are then sorted in a common table in the database.

Cluster Table:

Cluster tables are logical tables that must be assigned to a table cluster when they are defined.

Cluster tables can be used to strore control data.

They can also be used to store temporary data or texts, such as documentation.

A transparent table is a table that stores data directly.

You can read these tables directly on the database from outside SAP with for instance an SQL statement.

Transparent table is a one to one relation table

i.e. when you create one transparent table then exactly same table will create in data base

and if is basically used to store transaction data.

A clustered and a pooled table cannot be read from outside SAP

because certain data are clustered and pooled in one field.

One of the possible reasons is for instance that their content can be variable in length and build up.

Database manipulations in Abap are limited as well.

But pool and cluster table is a many to one relationship table.

This means many pool table store in a database table which is know as table pool.

All the pool table stored table in table pool does not need to have any foreign key relationship

but in the case of cluster table it is must.

And pool and cluster table is basically use to store application data.

Table pool can contain 10 to 1000 small pool table which has 10 to 100 records.

But cluster table can contain very big but few (1 to 10) cluster table.

For pool and cluster table you can create secondary index

and you can use select distinct, group for pool and cluster table.

You can use native SQL statement for pool and cluster table.

A structure is a table without data.

It is only filled by program logic at the moment it is needed starting from tables.

A view is a way of looking at the contents of tables.

It only contains the combination of the tables at the basis and the way the data needs to be represented.

You actually call directly upon the underlying tables.

Transparent table:

Tables can be defined independently of the database in the ABAP Dictionary.

The fields of the table are defined together with their (database-independent) data types and lengths.

A table definition in the ABAP Dictionary has the following components:

Table fields: The field names and the data types of the fields contained in the table are defined here.

Foreign keys: The foreign keys define the relationships between this table and other tables.

Technical settings: The technical settings define how the table is created on the database.

Indexes: Indexes can be defined for the table to speed up data selection from the table.

There are three categories of database tables in the ABAP Dictionary.

A physical table definition is created in the database for the table definition stored

in the ABAP Dictionary for transparent tables when the table is activated.

The table definition is translated from the ABAP Dictionary to a definition of the particular database.

On the other hand, pooled tables and cluster tables are not created in the database.

The data of these tables is stored in the corresponding table pool or table cluster.

It is not necessary to create indexes and technical settings for pooled and cluster tables.

Pooled table

Pooled tables can be used to store control data

(e.g. screen sequences, program parameters or temporary data)..

Several pooled tables can be combined to form a table pool.

The table pool corresponds to a physical table on the database in which all the records of the

allocated pooled tables are stored.

Cluster table

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.

Regards

Reshma

[Former Member]

Cluster Tables and pooled tables contain control information.

Cluster tables contains fields tat are dependent on primary key fields .

Pooled tables contains fields tat are not dependent on primary key fields mostly these tables contain primary key fields.

[Former Member]

hi...

<b>cluster table :</b>

A cluster table has many to 1 relationship...

A few tables in the R/3 DDIC .. but only one table in DATABASE...

And i think cluster tables shud have atleast one primary key in common

Cluster table are much more complex and you cannot display the data of a cluster table directly....

Cluster table have to be read and displayed via your ABAP program...

To find the cluster behind a cluster table, just go to the attributes of the table.

or go thro these information i got abt cluster table.

A table cluster is used to combine several tables. In the process several lines from different tables are combined in a single record. The records of all tables combined in a table cluster are stored in one table in the database.

A cluster contains a transparent cluster key which must be the first part of the key of all tables assigned to the cluster.

A table cluster also has a long field which contains the data from the tables on this key. If the data does not fit into this field, continuation records are created.

Also,

<b>Pooled Table</b> : Pooled tables are logical tables that must be assigned to a table pool when they are defined. Pooled tables are used to store control data. Several pooled tables can be cominied in a table pool. The data of these pooled tables are then sorted in a common table in the database.

The definition of a pool consists essentially of two key fields (Tabname and Varkey) and a long argument field (Vardata).

Example : Pool table : MDTC

example for cluster table:

BSEG is a cluster table consisting data from tables

BSID,BSAD,BSIS,BSAS,BSIK,BSAK which all are transperent tables.

jus check this link:

http://www.sap-img.com/abap/the-different-types-of-sap-tables.htm

this link wil clearly explain the differnces between all the types of tables.!!

*****Reward points if u find my asnwers useful...

all the best.