topic Re: Diff. Between Pool & Cluster Table in Application Development and Automation Discussions

Diff. Between Pool & Cluster Table

Former Member — Mon, 19 Dec 2005 06:32:56 GMT

Hi,

Could any just let me know regarding the Basic Diff. B/w

Pool & Clsuter Table.

Thanks & Regards

Irfan Hussain

Re: Diff. Between Pool & Cluster Table

amit_khare — Mon, 19 Dec 2005 06:37:45 GMT

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.

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.

Hope this will help.

Regards,

Amit

Re: Diff. Between Pool & Cluster Table

Former Member — Mon, 19 Dec 2005 06:38:43 GMT

Hi,

Table Pools

The data is stored as a table pool in the database server which consists of

all the (physical) records from the tables present in that particular table pool.

Technically, The table name and the field name are the key fields in case

of pooled tables.

Table Clusters

Logical data records from different tables are stored as single PHYSICAL record

in the table clusters.

Technically. There can be n number keys (usually generated by the system ) for a

record in a cluster table and field called pageno is used to track the continuation

of the records.

BOTH TABLE POOLS AND TABLE CLUSTERS ARE NOT PHYSICALLY AVAILABLE IN THE DB SERVER

BUT THEY ARE LOGICALLY POOLED OR CLUSTERED.

Pooled tables in the dictionary has a many-to-one relation with the table in database. Table in the database has the different name as in the dictionary.

A pooled table is used to combine several logical tables in the ABAP/4 dictionary. Pooled tables are logical tables that must be assigned to a table pool when they are defined.

Cluster tables:

Cluster table are logical tables that must be assigned to a table cluster when they are defined.

Cluster table can be used to store control data they can also used to store temporary data or text such as documentation

Thanks,

If this helps u reward with points.

Re: Diff. Between Pool & Cluster Table

Former Member — Mon, 19 Dec 2005 06:45:40 GMT

Hi Irfan,

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 pool or table cluster should be used exclusively for storing internal control information (screen sequences, program parameters, temporary data, continuous texts such as documentation). Data of commercial relevance is usually stored in transparent tables.

<b>Table Pool</b>

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).

<b>Cluster table:</b>

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.

Hope this helps u,

Regards,

Nagarajan.

Re: Diff. Between Pool & Cluster Table

Former Member — Mon, 19 Dec 2005 07:01:09 GMT

Hi Irfan,

Pooled Table :-

A pooled table in R/3 has a many-to-one

relationship.

When you look at a pooled table in R/3, you see a

description of a table.

R/3 uses table pools to hold a large number (tens to

thousands) of very small tables (about 10 to 100

rows each).

Table pools reduce the amount of database resources

needed when many small tables have to be open at the

same time.

SAP uses them for system data.

You might create a table pool if you need to create

hundreds of small tables that each hold only a few

rows of data.

Pooled tables are primarily used by SAP to hold

customizing data.

Cluster Table :-

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.

It holds many tables within it.

The tables it holds are all cluster tables.

Like pooled tables, cluster tables are another

proprietary SAP construct.

They are used to hold data from a few (approximately

2 to 10) very large tables.

They would be used when these tables have a part of

their primary keys in common, and if the data in

these tables are all accessed simultaneously.

Table clusters contain fewer tables than table pools

and, unlike table pools, the primary key of each

table within the table cluster begins with the same

field or fields.

A cluster is advantageous in the case where data is

accessed from multiple tables simultaneously and

those tables have at least one of their primary key

fields in common.

Cluster tables reduce the number of database reads

and thereby improve performance.

Pooled and cluster tables are usually used only by

SAP and not used by customers, probably because of

the proprietary format of these tables within the

database and because of technical restrictions

placed upon their use within ABAP/4 programs.

Cluster table can only be read and display via your

ABAP program.

For furthur details visit this link...

<a href="http://www.sap-img.com/abap/the-different-types-of-sap-tables.htm">http://www.sap-img.com/abap/the-different-types-of-sap-tables.htm</a>

Best Regards,

Maheswaran.B

Re: Diff. Between Pool & Cluster Table

Former Member — Mon, 19 Dec 2005 07:41:24 GMT

Hi Irfan,

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.

Regards,

Amit M.