Pool and Cluster tables

[peter_strauss]

Hello,

Why do we use pooled and cluster tables?

I have heard that these logical tables came about as the consequence of a historical limitation on the number of columns possible for a single table (I believe the restriction was 255).

I have checked tables contained in table pool KAPOL for example and found that the tables contained did not have 255 rows anyway.

Why not just simply define all of the pool and cluster tables as transparent tables?

Is there any merit to using logical tables?

Kind regards,

Peter Strauss

[Former Member · Accepted solution]

Hi Peter,

you're right, the tables where designed to overcome limitations of the databases when R/3 was developed. But both types are designed for different purposes.

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.

Regards

Ralph

[peter_strauss]

Hello Ralph,

Thank you!

Regards,

Peter