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Hierarchy relationship in data type.

Type

Hierarchy of type

The hierarchy of type defines how the types are implicitly converted. Implicit conversion is allowed for types from child to an ancestor. Example of Hierarchy for Hive: 

Primitive Type > Number > DOUBLE > FLOAT > BIGINT > INT > SMALLINT > TINYINT
                                 > STRING
               > BOOLEAN

Note that the type hierarchy allows the implicit conversion of STRING to DOUBLE.

Hierarchy of class

More generally, every type may be organised in a hierarchy using a inheritance design. Example in Java: Java - (Inheritance|Class Hierarchy) - (Subclass|Superclass) - (Extends, Super) - ( is a relationship)