Entity:
  columns:
    username: string(20)
    password: string(16)
    created_at: timestamp
    updated_at: timestamp

Child1:
  inheritance:
    extends: Entity
    type: column_aggregation
    keyField: type
    keyValue: 1

Child2:
  inheritance:
    extends: Entity
    type: column_aggregation
    keyField: type
    keyValue: 2