They cannot be directly managed by database system tools.
Administration of cluster tables is easier because the tables are not created separately, like transparent tables in a database.
Functionally dependent data stored in cluster tables may be read together, thus reducing access to the database.
Like pool tables, indexes for non-key fields cannot be created. However, primary or other indexes can be created for a set of fields that are to be key fields.
Database views, join statements or append statements cannot be used on these tables.
