topic Re: Difference between Cluster table & Pooled Table in Application Development and Automation Discussions

Difference between Cluster table & Pooled Table

Former Member — Thu, 18 Jan 2007 12:29:06 GMT

Can any give a right difference between cluster and pooled table

Re: Difference between Cluster table & Pooled Table

Former Member — Thu, 18 Jan 2007 12:31:35 GMT

FOr Tables

http://www.erpgenie.com/abap/tables.htm

For Tables

Pooled Tables, Table Pools, Cluster Tables, and Table Clusters

These types of tables are not transparent in the sense that they are not legible or manageable directly using the underlying database system tools. They are managed from within the R/3 environment from the ABAP dictionary and also at runtime when they are loaded into application memory.Pool and cluster tables are logical tables. Physically, these logical tables are arranged as records of transparent tables. The pool and cluster tables are grouped together in other tables, which are of the transparent type. The tables that group together pool tables are known as table pools, or just pools; similarly, table clusters, or just

clusters, are the tables which group cluster tables.Not all operations that can be performed over transparent tables can be executed over pool or cluster tables.

For instance, you can manage these tables using Open SQL calls from ABAP, but not Native SQL.These tables are meant to be buffered and loaded in memory, because they are commonly used for storing internal control information and other types of data with no external (business) relevance. SAP recommends that tables of pool or cluster type be used exclusively for control information such as

program parameters, documentation, and so on. Transaction and application data should be stored in transparent tables.

Table Pools

From the point of view of the underlying DBMS as from the point of view of the ABAP dictionary, a table pool is a transparent table containing a group of pooled tables which, when created, were assigned to this table pool.

Field Type Description

TABNAME CHAR(10) Table name

VARKEY CHAR(n) Maximum key length n =< 110

DATALN INT2(5) Length of the VARDATA record returned

VARDATA RAW(m) Maximum length of the data varies according to DBMS

Table Clusters

Similarly to pooled tables, cluster tables are logical tables which, when created, are assigned to a table cluster. Therefore, a table cluster, or just cluster, groups together several tables of type clusters.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.A cluster contains a transparent cluster key which must be located at the start of the key of all logical cluster tables to be included in the cluster. As well, a cluster contains a long field (VARDATA), which contains the

data of the cluster tables for this key. If the data does not fit into a field, continuation records are created.

Field Type Description

CLKEY1 CHAR(*) First key fields

CLKEY2 CHAR(*) Second key field

CLKEYN CHAR(*) nth key field

PAGENO INT2(5) Number of the next page

TIMESTMP CHAR(14) Time stamp

PAGELG INT2(5) Length of the VARDATA record returned

VARDATA RAW(*) Maximum length of the data section; varies according to database system

Working with Tables

The dictionary includes many functions for working with tables. There are five basic operations you can perform on tables: display, create, delete, modify, copy. Please do not confuse displaying a table with displaying the table entries (table contents). In order to display a table, it must previously exist; otherwise the system will display an error message in the status bar. For the following example, the table TABNA is used. To display this table, from the main dictionary screen, enter the table name in the Object name

input field with the radio button selected next to Tables. Then, click on the Display button at the bottom of the screen, or press the F7 function key, or, alternatively,

select Dictionary object Display from the menu.

In this screen, you can see table information such as

¨ Table type, shown next to the name of the object. In the example, it is a transparent table.

¨ Short text description.

¨ Name of the user who made the last change, and the date of the change.

¨ Master language.

¨ Table status. On the screen, you can see this table is saved and active.

¨ Development class. For information on development classes, refer to Chap. 6.

Delivery class, which sets the maintenance group for the table. It controls how tables will behave during client copy procedures, upgrades, and so forth.¨

Tab. Maint. Allowed flag, which indicates whether you can generate a screen for maintaining table entries.

¨Then, on the lower part of the screen, you can see the table fields with all associated characteristics such as:

¨ Field name.

¨ Key indicator. When set, this field is the primary key, or part of it.

¨ Data element.

¨ Basic data type.

¨ Length.

¨ Check table.

¨ Short text, describing the field.

Additional information about the table can be displayed by selecting the corresponding functions from the menu or directly from the application toolbar, such as keys, indexes, or technical settings.

Regards,

Balaji

**Rewards for helpful answers

Re: Difference between Cluster table & Pooled Table

Former Member — Thu, 18 Jan 2007 12:31:46 GMT

Hi Vighnesh ,

A major diffrence between the two is in case of cluster tables there must be some relationship ( a common filed) between the tables which form the cluster , but this is not required in case of Pool tables.

Second is cluster table store very large volume of data , where as pooltables are usually creeted by pooling together those table where the volume of data and modification/updates to data is less.

Regards

Arun

Re: Difference between Cluster table & Pooled Table

Former Member — Mon, 16 Apr 2007 05:06:04 GMT

hiiiiiii

3rd difference is poole n transparent table has buffer while cluster don't

Re: Difference between Cluster table & Pooled Table

Former Member — Mon, 16 Apr 2007 05:08:25 GMT

Hi,

1. First thing to understand is this that

Either Pooled data, or cluster Data.

Both have SOME PHYSICAL table in the database.

(The table name will be different)

2. POOL TABLE

Suppose we have 15 different

tables in ABAP Dictionary

and only 1 table in physcial table.

So, the data of all these 15 tables

will be stored in the 1 physical table.

(it will be stored in a raw data format,

but it will be provided to the programs

in a structured way)

This concept is called POOL.

If all these 15 tables have 10 records each,

Then,

In the poooled table there will be

15 x 10 = 150 records.

Each record of the physical table

contains,

name of the table

Primary key value of the table

so that to identify the record.

3. CLUSTER

In a cluster table,

there is 1 physical table.

Each record contains a RAW Data.

The format of raw data is such

that it contains (NESTED DEEP STRUCTURE)

ie.

this raw data of 1 record,

contains data of many INTERNAL TABLES.

(These tables are just defined as structure

in database dictionary so that its definition

is there while saving and extracting)

Eg.

Salary of 1 employee, 1 month

will have 1 record in database table.

But this 1 record raw data will contain

information about these many internal tables.

Company data

salary figures

bank figures data

Provident fund data

etc. etc.

I hope it helps.

Kishi.

Re: Difference between Cluster table & Pooled Table

Former Member — Mon, 16 Apr 2007 05:12:03 GMT

vignesh,

1. First thing to understand is this that

Either Pooled data, or cluster Data.

Both have SOME PHYSICAL table in the database.

(The table name will be different)

2. POOL TABLE

Suppose we have 15 different

tables in ABAP Dictionary

and only 1 table in physcial table.

So, the data of all these 15 tables

will be stored in the 1 physical table.

(it will be stored in a raw data format,

but it will be provided to the programs

in a structured way)

This concept is called POOL.

If all these 15 tables have 10 records each,

Then,

In the poooled table there will be

15 x 10 = 150 records.

Each record of the physical table

contains,

name of the table

Primary key value of the table

so that to identify the record.

3. CLUSTER

In a cluster table,

there is 1 physical table.

Each record contains a RAW Data.

The format of raw data is such

that it contains (NESTED DEEP STRUCTURE)

ie.

this raw data of 1 record,

contains data of many INTERNAL TABLES.

(These tables are just defined as structure

in database dictionary so that its definition

is there while saving and extracting)

Eg.

Salary of 1 employee, 1 month

will have 1 record in database table.

But this 1 record raw data will contain

information about these many internal tables.

Company data

salary figures

bank figures data

Provident fund data

etc. etc.

Don't forget ot reward if useful

Re: Difference between Cluster table & Pooled Table

Former Member — Mon, 16 Apr 2007 06:24:32 GMT

hi...

cluster table :

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,

pool table :

(i found these details by searching the net)

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.

reward points if u find my asnwers useful...

all the best.

Re: Difference between Cluster table & Pooled Table

Former Member — Mon, 16 Apr 2007 18:57:12 GMT

refer this link

http://www.is-edu.hcmuns.edu.vn/WebLib/Books/Database/0-672-31217-4/ch03/ch03.htm#TableClustersandClusterTables