difference between transparent, pooled and cluster tables......

[Former Member]

HI,

can any body tell me the difference between transparent, pooled and cluster tables.in detail and also their advantages and usage.

thanks in advance.

[Former Member]

Hi,

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.

Message was edited by:

Dhananjay Patil

[Former Member]

Hi

There are three types of tables.

1. Transparent Table

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

2. 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.

3. 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.

The major difference between transparent tables, pooled tables and clusterd Tables are:

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.

Regards

vasu

[Former Member]

thanks, but i want the exact functionality and also the use of these...

[Former Member]

can i create a view on two or more pooled or cluster tables....

[Former Member]

Hi,

Generally we play with Transparant tables only..

Cluster and pooled tables are system tables used by system internally...

pooled and cluster tables are usually used only by sap and not used by customer, probably because of the proprietary format of these tables within the database and because of technical resriction put on them for their usage in abap program..

Message was edited by:

Dhananjay Patil

[Former Member]

The following are the table types used in SAP :

I. Transparent tables (BKPF, VBAK, VBAP, KNA1, COEP)

Allows secondary indexes (SE11->Display Table->Indexes)

Can be buffered (SE11->Display Table->technical settings) Heavily updated tables should not be buffered.

II. Pool Tables (match codes, look up tables)

Should be accessed via primary key or

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

No secondary indexes

Select * is Ok because all columns retrieved anyway

III. Cluster Tables (BSEG,BSEC)

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

No secondary indexes

Select * is Ok because 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

IV. Buffered Tables (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.

Transparent table - many to many

pooled - many to one

cluster table - many to one

poolled and cluster table both are logical tables

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.

A001,A004,A005,A006,A007,A009,A010,A012,A015,A016,A017,A018,A019,A021,A022,

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.

AUAA,AUAB,AUAO,AUAS,AUAT,AUAV,AUAW,AUAY,BSEC,BSED,BSEG,BSES,BSET,CDPOS

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

Thanks

Seshu

[Former Member]

HI,

<b>transparent table:</b>

A transparent table in the dictionary has a one-to-one relationship with a table in the database. Its structure in R/3 Data Dictionary corresponds to a single database table. For each transparent table definition in the dictionary, there is one associated table in the database. The database table has the same name, the same number of fields, and the fields have the same names as the R/3 table definition. When looking at the definition of an R/3 transparent table, it might seem like you are looking at the database table itself.

<b>pooled tables:</b>

A pooled table in R/3 has a many-to-one relationship with a table in the database (see Figures 3.1 and 3.2). For one table in the database, there are many tables in the R/3 Data Dictionary. The table in the database has a different name than the tables in the DDIC, it has a different number of fields, and the fields have different names as well. Pooled tables are an SAP proprietary construct.

<b>cluster tables:</b>

A cluster table is similar to a pooled table. It has a many-to-one relationship with a table in the database. Many cluster tables are stored in a single table in the database called a table cluster.

rgds,

bharat.