data dictionary

[Former Member]

what is the difference b/w the pooled tables and cluster tables.

can we write open sql statements to these tables and can we write inner join for these tables . where exactly data will be stored in these tables.

[Former Member]

Hi,

follow this link...

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

regards,

Ashok Reddy

[Former Member]

<b>What is cluster and pool table? Where and when we use these tables?</b>

<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.

<b>Cluster Table</b> : 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.

<b>what is the major difference between Standard tables, Pooled tables and Clusterd Tables?</b>

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. <b>You can use native SQL statement for pool and cluster table. </b>

<b>Note :</b>

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 in the database in which all records from the pooled tables assigned to the table pool are stored corresponds to a table pool.

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

Table Clusters 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.

<b>can we write open sql statements to these tables and can we write inner join for these tables . where exactly data will be stored in these tables</b>

Yes .... You can use native SQL statement for pool and cluster table. the data is stored in the database of there own tables without any secondary index .

reward points if it is usefull .....

Girish

[Former Member]

Hi Bhagavan,

<b> I. Pool Tables (</b>match codes, look up tables)

Should be accessed via primary key or

Should be buffered (SE11->Display Table->technical settings)

No secondary indexes

<b>Select * is Ok because</b> all columns retrieved anyway

<b>II. Cluster Tables (BSEG,BSEC)</b>

Should be accessed via primary key - very fast retrieval otherwise very slow

No secondary indexes

<b>Select * is Ok because</b> all columns retrieved anyway. Performing an operation on multiple rows is more efficient than single row operations. Therefore you still want to select into an internal table. If many rows are being selected into the internal table, you might still like to retrieve specific columns to cut down on the memory required.

Statistical SQL functions (SUM, AVG, MIN, MAX, etc) not supported

Can not be buffered

<b>III.</b> <b>Buffered Tables</b> (includes both Transparent & Pool Tables)

While buffering database tables in program memory (SELECT into internal table) is generally a good idea for performance, it is not always necessary. Some tables are already buffered in memory. These are mostly configuration tables. If a table is already buffered, then a select statement against it is very fast. To determine if a table is buffered, choose the 'technical settings' soft button from the data dictionary display of a table (SE12). Pool tables should all be buffered.

<b>Reward pts if found usefull</b>

Regards

Sathish

[Former Member]

Hi,

please check out the link below it might help you in knowing the difference between pool and cluster table

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

for more information on pool and cluster table please check out the link below it might help you

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

We can use native SQL statementas well as for pool and cluster table, so we can use select query for data processing.

**************please reward points if the information is helpful to you**************

[Former Member]

<b> What are pooled tables?</b>

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).

<b> What is a table cluster?</b>

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.

<b><i>do give point if helpful

Debjani</i></b>