Pool and Cluster table..

[Former Member]

hi,

Can any one explain me how to read the data from the Pool table and cluster table with the example of Select query..

thnx

[Former Member]

check out these related threads

Pooled & Clustered Tables

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

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

Tables Documentation

https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/25c1f5d1-0901-0010-d495-e96d02a0...

Please give me reward points...

Pool tables are defined to host lots of small tables. The reason for them is to reduce the number of tables in the database. In 1992 databases could not handle that number of tables R/3 needed. Even today you see problems due to the high number of tables in SAPs applications. Just watch out for Notes regarding problems with catalog tables or views on an Oracle database. Some of the tables originally placed in Pool tables are later converted to transparent tables, for performance reasons.

Cluster tables where those tables designed for this other restriction you heard from (more than 255 fields). But they have other advantages too. They store information's belonging together in the same database blocks, this improves also performance when you read them.

[Former Member]

Pool 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.

cluster table bseg