Within a namespace, no two objects can have the same name.
The following schema objects share one namespace:
Each of the following schema objects has its own namespace:
Clusters
Constraints
Database triggers
Dimensions
Indexes
Materialized views (When you create a materialized view, the database creates an internal table of the same name. This table has the same namespace as the other tables in the schema. Therefore, a schema cannot contain a table and a materialized view of the same name.)
Private database links
Because tables and sequences are in the same namespace, a table and a sequence in the same schema cannot have the same name. However, tables and indexes are in different namespaces. Therefore, a table and an index in the same schema can have the same name.
Each schema in the database has its own namespaces for the objects it contains. This means, for example, that two tables in different schemas are in different namespaces and can have the same name.
Each of the following nonschema objects also has its own namespace:
Because the objects in these namespaces are not contained in schemas, these namespaces span the entire database.