Table inheritance
Only tables that are defined
on named row types support table inheritance. Table inheritance
is the property that allows a table to inherit the behavior (constraints,
storage options, triggers) from the supertable above it in the table
hierarchy. A table hierarchy is the relationship that you can
define among tables in which subtables inherit the behavior of supertables.
A table inheritance provides the following advantages:
- It encourages modular implementation of your data model.
- It ensures consistent reuse of schema components.
- It allows you to construct queries whose scope can be some or all of the tables in the table hierarchy.
In a table hierarchy, a subtable automatically
inherits the following properties from its supertable:
- All constraint definitions (primary key, unique, and referential constraints)
- Storage option
- All triggers
- Indexes
- Access method