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Object-Based Databases - Coggle Diagram

- - - - The simplest, but least convenient, way is to declare
        that a class is persistent.
    - - new syntax is introduced to create persistent objects, by extending the syntax for creating transient objects
    - - A variant of the preceding approach is to mark
        objects as persistent after they are created.
    - - One or more objects are explicitly declared as persistent objects.
  - - - Intraprogram.
        
        Identity persists only during the execution of a single program or query
      - Intraprocedure
        
        Identity persists only during the execution of a single procedure.
      - Interprogram.
        
        Identity persists from one program execution to another.
      - Persistent
        
        Identity persists not only in program executions but also in structural reorganizations of the data.
  - - - expose object identifiers or persistent pointers to the objects, which can be stored externally
      - Give names to objects, just as we give names to files
      - store collections of objects, and to allow programs to iterate
        over the collections to find required objects.
  - - - Persistent pointers
      - Creation of persistent objects
      - Class extents
      - Relationships
      - Iterator interface
      - Transactions
      - Updates
      - Query language
  - - - Byte code enhancement
        
        classes whose objects may be made persistent are specified in
        a configuration file .
      - Database mapping
        
        JDO does not define how data are stored in the back-end
        database.
      - Persistence by reachability
        
        Objects are not explicitly created in a database
      - Class extents
        
        Class extents are created and maintained automatically for
        each class declared to be persistent.
      - Single reference type
        
        There is no difference in type between a reference to
        a transient object and a reference to a persistent object.
- - - - Complex data types, integration with programming language, high performance.
    - - Complex data types, powerful query languages,
        high protection
    - - Simple data types, powerful query languages, high protection.
    - - Complex data types integrated with
        programming languages
- - - - an unordered collection,