Garcia Molina et al 2003 Practically ORDBMS bridges the gap between OODBMS and

Garcia molina et al 2003 practically ordbms bridges

This preview shows page 2 - 4 out of 11 pages.

now called “object-relational.” (Garcia-Molina, et al. 2003). Practically, ORDBMS bridges the gap between OODBMS and RDBMS by allowing users to take advantage of OODB'MSs great productivity and complex data type without losing their existing investment in relational data (Connolly & Begg, 2006). In fact, an ORDBMS engine supports both relational and object-relational features in an integrated fashion (Frank, 1995). The underlying ORDB data model is relational because object data is stored in tables or columns. ORDB designers can work with familiar tabular structures and data definition languages (DDLs) while assimilating new object-oriented features (Krishnamurthy et al., 1999).It is essentially a relational data model with object-oriented extensions. In response to the evolutional change of ORDB technology, SQL:1999 started supporting object-relational data modeling features in database management standardization and SQL:2003 continues this evolution. Currently, all the major database vendors have upgraded their relational database products to object-relational database management systems to reflect the new SQL standards (Hoffer et al., 2009) and use by industrial practitioners. Although each of the object-relational DBMS vendors has implemented OO principles: encapsulation and inheritance in their own way, all of them share the combination of the OO principles and follow SQL standardization, incorporate object-oriented paradigms. All the ORDBMSs have the ability to store object data and methods in databases. Many of the SQL:2003 standard ORDBMS features appear in Oracle. These features are listed as follows. Object Types : User-defined data types (UDT) or abstract types (ADT) are referred to as object types. Functions/Methods: For each object type, the user can define the methods for data access. Methods define the behavior of data.
Image of page 2
Information Systems Education Journal (ISEDJ) 9 (4) September 2011 © 2011 EDSIG (Education Special Interest Group of the AITP) Page 82 / Varray : The varray is a collection type that allows the user to embed homogenous data into an array to form an object in a pre-defined array data type. Nested table: A nested table is a collection type that can be stored within another table. With a nested table, a collection of multiple columns from one table can be placed into a single column in another table. Inheritance : With Object type inheritance, users can build subtypes in hierarchies of database types in ORDBs. Object View : Object view allows users to develop object structures in existing relational tables. It allows data to be accessed or viewed in an object-oriented way even if the data are really stored in a traditional relational format. There is some research that has been done in ORDBMS technology as ORDBMSs have become commonplace in recent years. He and Darmont (2005) propose the Dynamic Evaluation Framework (DEF) that simulates access pattern changes using configurable styles of change.
Image of page 3
Image of page 4

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture