Pooled and Cluster Tables

Pooled Tables
A pooled table is a special type of table available in the SAP ABAP dictionary. The pooled table is a proprietary SAP creation and has many-to-one relationships with tables in the SAP database. This means that for a given pooled table in the database, there could be many smaller tables in the SAP data dictionary. SAP uses pooled tables for integrating and holding a large number of small tables. This helps in reducing the space and resources needed at the database level. SAP mostly uses pooled tables for maintaining system data.

Cluster Tables
Several logical data records from different cluster tables can be stored together in one physical record in a table cluster.