Difference b/w clustered and pooled table

[Former Member]

Hi,

Difference b/w clustered and pooled table?

I need brief explanation.

[Former Member]

Hi,

Difference b/w clustered and pooled table?

I need brief explanation.

[Former Member]

Hello,

The idea of <b>cluster tables</b> is that you store functionally dependent data which is divided among different tables in one database table. Accordingly, the intersection of the key fields of the cluster tables is formed by the key of the table cluster (cluster key).

The basic idea of a <b>table pool</b>, as opposed to table clusters, is the storage of data records from the tables defined in the ABAP Dictionary that are not dependent on one another. You would like to combine small R/3 tables to a database table.

More...

The decisive advantage of pool and cluster tables is that the data can be stored in compressed form in the database. This reduces the memory space required

as well as the network load.

The combination of tables into table pools to table clusters means less tables and the compressing means less fields in the database. The result is that fewer different

SQL statements are carried out.

Pool and cluster tables are not stored as separate tables in the database. In this way, the administration becomes simpler. With cluster tables, functionally dependent

data are read together, which results in fewer database accesses.

The decisive disadvantage lies in the restricted database functionality. It is not possible for non-key fields to create an index. There are neither primary indices

nor indices on a subset of the key fields. The use of database views or ABAP JOINs is also ruled out, as are Table Appends. You can access the data in pool or

cluster tabels only via OPEN SQL (no Native SQL).

For pool tables, only the WHERE conditions for key fields and for pool tables,only the WHERE conditions for the fields of the cluster key (subset of the key

fields) are transferred to the database. ORDER BY (or GROUP BY) clauses are not transferred for non-key fields. You need longer keys than semantically necessary for pool tables.

Reward if helpful,

Regards,

LIJO

[Sandeep_Panghal]

Hi,

Cluster table :Database table defined in the ABAP Dictionary, whose version on the database is not only assigned to one table defined in the ABAP Dictionary. Several cluster tables are assigned to a table cluster in the database. The intersection of the key fields of the cluster tables forms the primary key of the table cluster. The other columns of the cluster tables are stored in compressed form in a single column VARDATA of the table cluster. You can access cluster tables only via Open SQL, and only without using joins.

Pooled table : A database table defined in the ABAP Dictionary whose database instance is assigned to more than one table defined in the ABAP Dictionary. Multiple pool tables are assigned to a table pool in the database. The key fields of a pool table have to be character-type fields. The table pool's primary key consists of two fields: TABNAME for the name of a pool table, and VARKEY for the interdependent contents of the key fields in the corresponding pool table. The non-key fields of the pool table are stored in compressed format in their own column, called VARDATA, of the table pool. The only way to access pool tables is by using Open SQL. Joins are not allowed.

*reward if helpful!

[Former Member]

hi udaya,

Pooled and Cluster Tables

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.

Table Pools

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).

All the cluster tables in a table clustor will have one or more common fields. Whereas pooled tables in table pool need not to have common field.

regards,

amit m.

[Former Member]

hi,

pool tables: used for system purpose to store system information such as screen no's , field names, screen sequences, select options value,............................... . a group of pool tables form as table pool. they reside at application server level. only useful for system purpose. nothing to do for sap user. they may not have primary key fields and also some times index is also not required. for ex: a pool table is given as in case of module pool

when we used 'CALL SCREEN' st then system transfers control of current execution to callesd screen. in such cases it creates pool table and stores all screen fields and where it left execution and screen sequences that taken for new screen ....................

cluster tables: generally used for system purposes. when u pressed F4 button on a table field for which search help is attached u ll get information for that field with the help of cluster table only. system creates a cluster table with which all primary key fields are linked and index is maintained for it. a gorup of cluster tables form a cluster pool. mainly useful in providing search helps to the fields .

if helpful rewrad some points.

with regards,

Suresh Aluri.