The objects in a relational database are organized into sets called collections. A collection provides a logical classification of objects in the database. A collection is also called a schema.
When a table, view, index, alias, procedure, user-defined function, or user-defined data type is created, it is assigned to exactly one collection. The collection to which an object is assigned is determined by the name of the object. For example, CREATE TABLE C.X creates table X in collection C.