Solved: pool and cluster table

Former Member · ‎2008 May 28

hi all,

can anyone tell me that why we need pool and cluster table?

is it neccessary to have pool and cluster table?

regards saurabh.

Former Member · ‎2008 May 28

Hi,

Need of POOl & CLUSTER Tables

I heard that these logical tables came about as the consequence of a historical limitation on the number of columns possible for a single table (I believe the restriction was 255).

I have checked tables contained in table pool KAPOL for example and found that the tables contained did not have 255 rows anyway.

pool and cluster table were designed to overcome limitations of the databases when R/3 was developed. But both types are designed for different purposes.

Pool tables are defined to host lots of small tables. The reason for them is to reduce the number of tables in the database. In 1992 databases could not handle that number of tables R/3 needed. Even today you see problems due to the high number of tables in SAPs applications. Just watch out for Notes regarding problems with catalog tables or views on an Oracle database. Some of the tables originally placed in Pool tables are later converted to transparent tables, for performance reasons.

Cluster tables where those tables designed for this other restriction you heard from (more than 255 fields). But they have other advantages too. They store information's belonging together in the same database blocks, this improves also performance when you read them.

Regards,

Raj.

Former Member · ‎2008 May 28

Hi

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 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.

Regards,

Jay

Former Member · ‎2008 May 28

Hi,

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.