Database type independence

From: Fredrik Bertilsson (fredrik_bertilsson_at_passagen.se)
Date: 08/22/04 

Date: 22 Aug 2004 07:07:46 -0700

Many OO evengalists argue very hard for making the persistance layer
independent of the database type (RDB, OODB, LDAP, etc). They want to
be able to change the database from a RDB to an OODB without changing
the business logic.

But the cost for doing this is very high. The developer is forced to
implement (or configure) an extra transformation/mapping layer. The
persistance frameworks becomes unnecessary complex. This requirement
about database type independance is one of the main reasons that EJB
is so very complex. Besides, data-aware components are not possible to
use because of this requirement.

My question is, is it really worth the cost to make the architecture
independant of database type. On the software market, there are a huge
demand for relational database vendor independant applications. Most
customers want to be able to run the applications they buy on their
favorite dbms system like Oracle, SQL Server, MySQL etc. But how many
customers want the application to be able to run on their OODB? I have
never heard about it anyway.

Relational databases have proven to be the superior database type.
They have almost 100% percent market share and this fact does not seem
to change in the near future. In fact relational databases is more
likely to live longer than most programming languages used today
(Java, C#, C++, PHP, VB etc). There have been numerous examples of
applications changing programming languages (from Cobol and Fortran to
Java or VB/C#) and the database remains the same. But the examples of
changing database type and keeping the application the same is
extremely few.

Is it really reasonable to invest money in a feature (database type
independence) that in almost no cases are needed? I think that if IT
managers really knew that when they are investing in mainstream OO
architecture, they are also spending money on things they will never
need, they would make different decisions.

It would be interesting if it is someone out there that actually uses
something else but relational databases for persistance? And in that
case, what type of applications and what database vendor. It would be
even more interesting to know if someone actually have changed from
relational database to OO database (or something else), whithout
having to rewrite the business logic.

/Fredrik

Relevant Pages

  • Re: Database type independence
    ... > independent of the database type (RDB, OODB, LDAP, etc). ... > implement an extra transformation/mapping layer. ... > about database type independance is one of the main reasons that EJB ...
    (comp.object)
  • Re: Database type independence
    ... > independent of the database type. ... > about database type independance is one of the main reasons that EJB ... > demand for relational database vendor independant applications. ... > Relational databases have proven to be the superior database type. ...
    (comp.object)
  • Re: Database type independence
    ... > independent of the database type (RDB, OODB, LDAP, etc). ... > about database type independance is one of the main reasons that EJB ... When you have a persistence layer, ...
    (comp.object)
  • Re: Database type independence
    ... > Many OO evengalists argue very hard for making the persistance layer ... > independent of the database type. ... naturally tends to be independent of database type as well. ... > Relational databases have proven to be the superior database type. ...
    (comp.object)
  • Re: What is an OODBMS?
    ... But to me it is still not clear what a OO database actually ... >the programming language. ... OODB - something that very very few people can do. ... PSE-Pro are good ...
    (comp.object)