Qustion on Dictionary

[Former Member]

1. what are the types of tables in abap? and give me the expalnation with example?

[Former Member]

1. what are the types of tables in abap? and give me the expalnation with example?

[rodrigo_paisante3]

Hi, welcome to SDN.

Try to use the forum, you can find the same question.

see this link:

[former_member188829]

Hi,

There r three types of Tables r there.

1)Transparent Table.

2)Cluster Table

3)Pooled Table.

[Former Member]

Hi Sunil,

Welcome to SDN!!!!!

<b>Transparent Table :</b> Exists with the same structure both in dictionary as well as in database exactly with the same data and fields.

<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.

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.

Thanks,

Vinay

[Former Member]

Hai sunil,

Types of tables are:

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.

Reward for useful answers

Regards,

sunil kairam.

[Former Member]

Type of a table or structure

The table type determines how the logical table description defined in the ABAP/4 Dictionary is reproduced on the database. There are the following table types:

transparent table

structure

append structure

For internal purposes, such as storing control data or update texts, there are in addition the following table types:

pooled table

cluster table

generated view structure

Transparent table: There is a physical table on the database for each transparent table. The names of the physical tables and the logical table definition in the ABAP/4 Dictionary correspond. All business data and application data are stored in transparent tables.

Structure: No data records exist in the database for a structure. Structures are used for the interface definition between programs or between screens and programs.

Append structure: An append structure defines a set of fields which belong to another table or structure but which are treated in the correction administration as its own object. Append structures are used to support modifications.

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.

Generated view structure: In activation a structure is generated for a view. This structure serves as interface for the runtime environment. It does not generally appear in the ABAP/4 Dictionary.

What is a Data Class?

The Data class determines in which tablespace the table is stored when it is created in the database. What is a Size Category? The Size category describes the probable space requirement of the table in the database. How Many types of size categories and data classes are there? There are five size categories (0-4) and 11 data classes, only three of which are appropriate for application tables:

- APPL0 - Master data (data frequently accessed but rarely updated)

- APPL1 - Transaction data (data that is changed frequnetly)

- APPL2 - Organisational data (customizing data that is entered when system is

configured and then rarely changed)

What are control tables?The values specified for the size category and data class are mapped to database-specific values via control tables.

What is a table pool?

A table pool (or pool) is used to combine several logical tables in the ABAP/4 Dictionary. The definition of a pool consists of at least two key fields and a long argument field (VARDATA).

What are pooled tables? 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).

What is a table cluster?

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.

Transparent Tables

There is a physical table on the database for each transparent table.

The names of the physical table and the logical table definition in the

ABAP/4 Dictionary agree. All the business and application data is store

in transparent tables.

Pooled tablePooled 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 category. This permits object-by-object storage or

object-by-object access. In order to combine tables in clusters, at

least part of the keys must agree. Several cluster tables are stored in

one corresponding table on the database.