Diadvantages of OODBMS

List the disadvantages of OODBMS / What are the disadvantages of OODBMS?

Disadvantages of Object Oriented DBMSs (OODBMS)

• Lack of universal data model and lack of standards – there is no universally agreed model for OODBMS.

• Lack of experience – not easy for an end user. We need programmers to interact.

• Competition – Object Relational DBMS (ORDBMS) are much more easier to use and capable of providing object facility to the end user.

• Query optimization compromises encapsulation – The query optimization process requires complete understanding about the database in terms of table information and size etc. Hence, we need to compromise encapsulation (encapsulation is a language mechanism for restricting access to some of the object's components).

• Locking at object level may impact performance

• Complexity – OODBMS concept implementation is complex.

• Lack of support for views – no support for views manipulation

• Lack of support for security

• Poor performance – query optimization for OODBMS is complex.

• Unable to support large-scale systems – scalability issue. 

Advantages of OODBMS

List the advantages of OODBMS / Advantages of Object Oriented Database Management Systems / Discuss the various advantages of OODBMS

Advantages of Object Oriented DBMSs (OODBMS)

• Enhanced modeling capabilities – it is easy to model the real-world object as close as possible like the case of Object Oriented Programming concepts.

• Extensibility – Support for new data types - Unlike traditional DBMS products where the basic data types are hard-coded in the DBMS and are unchangeable by the users, with an ODBMS the user can encode any type of structure that is necessary and the ODBMS will manage that type.

• Removal of impedance mismatch – Impedance mismatch is a set of conceptual and technical difficulties that are often encountered when a relational database management system (RDBMS) is being used by a program written in an object-oriented programming language or style; particularly when objects or class definitions are mapped in a straightforward way to database tables or relational schema. The DML of OODBMS can eliminate the difficulties.

• Expressive power – provides an ability to handle objects like records in RDBMS. Hence, OODBMS is more expressive than RDBMS. An object database stores complex data and relationships between data directly, without mapping to relational rows and columns, and this makes them suitable for applications dealing with very complex data.

• Support for schema evolution

• Support for long-duration transactions – the process of object data involves increased complexity. Hence, we need to provide support for long-duration transactions.

• Applicability to advanced database applications – enhanced modeling capabilities of OODBMS makes it usable to application like computer-aided design (CAD), computer-aided software engineering (CASE), office information systems (OISs), multimedia systems, and many more.

• Improved performance – improved performance in the case of object based applications.

• Reusability – the code can be reused. Inheritance, method support, etc enables the possibility of reusing the code. An OODBMS can be programmed with small procedural differences without affecting the entire system

• OODBs eliminate need for user defined keys - The OODB model has an OID that it is automatically generated by the system and that guarantees uniqueness to each object. This, in addition to eliminating the need for user defined keys in the OODB model, has brought other advantages to OODBs: 1) the OID cannot be modified by the application; 2) the notion of object identity provides a separate and consistent notion of identity, which is independent of how an object is accessed or modeled with descriptive data. Therefore, two objects are different if they have different OIDs, even if they have the same structures and the same values for all their properties.

• OODBs reduce need for Joins - The capability of navigating through object structures and the resulting path expressions in object attributes gives us a new perspective on the issue of joins in OODBs. The relational join is a mechanism that correlates two relations on the basis of values of a corresponding pair or attributes in the relations. Since two classes in an OODB may have corresponding pairs of attributes, the relational join (or, explicit join) may still be necessary in OODBs.

Object-Oriented Model Vs Relational Model

Object-Oriented Model Vs Relational Model

The major components of Object-oriented model and the Relational model are compared in the picture given below;
 

[Source: Colorado.edu]

Object Relational Database Management System (ORDBMS)

What is ORDBMS? / Define ORDBMS

ORDBMS

An object-relational database (ORD), or object-relational database management system (ORDBMS), is a database management system (DBMS) similar to a relational database, but with an object-oriented database model: objects, classes and inheritance are directly supported in database schemas and in the query language. [Source: Wikipedia]

Object Relational Database Management Systems (ORDBMSs) actually extend the RDBMS with the concepts like objects classes and inheritances etc.

This system simply puts an object oriented front end on a relational database (RDBMS). When applications interface to this type of database, it will normally interface as though the data is stored as objects. However the system will convert the object information into data tables with rows and colums and handle the data the same as a relational database. Likewise, when the data is retrieved, it must be reassembled from simple data into complex objects.

Some ORDBMSs - 

                            IBM, Informix, and Oracle.

* Advantages of ORDBMS
* Diadvantages of ORDBMS