11.3. Post-relational, multi-dimensional and object-oriented data representation models

The post- relational data representation model is an extended version of the relational data model and allows to eliminate the limitation of the indivisibility of data stored in table entries. That is why data storage in the post-relational model is considered more efficient than the relational one.

The advantage of the post-relational model is that it allows the formation of a set of related relational tables through a single post-relational table, which ensures high visibility of the presentation of information and the efficiency of its processing.

The disadvantage of such a model is the difficulty of solving the problem of ensuring the integrity and consistency of the stored data.

Examples of post-relational DBMS are the UniVers, Budda and Dasdb systems.

In 1993, an article by E. Codd was published, in which he formulated 12 basic requirements for OLAP-class systems (On-line Analytical Processing). The main principles described were related to the possibilities of conceptual representation and processing of multidimensional data. This moment became the starting point of growing interest in multidimensional data presentation models.

Multidimensional models are highly specialized DBMSs that are used for interactive analytical processing of information. The multidimensional organization of the data is more visually and informative in comparison with the relational model.

The main disadvantage of the multidimensional data model is its cumbersomeness for solving the simplest tasks of ordinary on-line information processing.

Examples of DBMSs based on such models are Ess-base from Arbor Software, Oracle Express Server from Oracle , etc.

Object-oriented data representation models allow you to identify individual database records. Certain relationships are formed between database entries and their processing functions using mechanisms similar to the corresponding tools in object-oriented programming languages.

The advantages of the object-oriented data model are:

1) the ability to display information about the complex relationships of objects;

2) the ability to identify an individual database record and determine the function of its processing.

The disadvantages of the object-oriented data model include:

1) difficulty in understanding its activities by non-professional users;

2) the inconvenience of data processing;

3) low speed query execution.

Among object-oriented DBMS, it is possible to distinguish the systems ROET of the company POET Software, Versant of the company Versant Technologies , etc.