Today I reviewed postgreSQL wiki and I found it is a ORDBMS (object-relational database management system), so I want to know is there any benefits for using postgreSql (RDBMS) behind the JPA (hibernate, eclipselink, ....) instead of a RDBMS (Mysql, ...) for performance issues or not?
As you know JPA use ORM and use JQL (java query language)
Regards
Object-Relational data is defined as structured data, which is user defined types in the database.
OR data types include:
These types are defined differently in each database, in Oracle they are OBJECT types, VARRAY types, and NESTED TABLE, and REF types.
JDBC standardizes access to OR data types using the Struct, Array and Ref interfaces.
With OR data-types you can have more complex database schemas, such as a TABLE of Employee_Type that has a Varray of Phone_Types and a Ref to it manager.
JPA does not have any direct support for mapping OR data-types, but some providers do.
EclipseLink has support for mapping OR data-types including, Structs, Ref, and Arrays. Custom mappings and annotations are used to map these, but the runtime JPA API is the same.
I would not normally recommend usage of OR data-types, as they are less standard than traditional relational tables, and do not give much benefit. Some database defined OR data-types, such as spatial data-types do offer advantages as they have integrated database support.
I would say no. JPA is targeted at RDBMSs, and doesn't use the additional capabilities offered by ORDBMSs.
Now, PostgreSQL is also a very good RDBMS (you're not forced to use its object-oriented features, and my guess would be that most of its users don't), and you may use it with JPA without problem.
JPA is the translator between "thinking in objects" (Java) and "thinking in relations" (SQL). Therefore a JPA implementation will always speak to the DB in terms of relations. "Object Relational" stuff is ignored here.
Ignoring JPA and talking directly to the DB in "ORDBMS" speak won't buy you performance benefits in the most common cases, because ORDBMS are still RDBMS with some glue logic to look a little bit object-stylish. The data is stored in relations, all access paths are the same as pure relational access path.
If you really want to see performance benefits by switching not only the database product but the database technology (or philosophy) you should look at real Object Databases or even NoSQL.
