Re: OO versus RDB

David Barrett-Lennard a écrit :
bruno at modulix wrote:

David Barrett-Lennard wrote:

Bruno Desthuilliers wrote:


David Barrett-Lennard a écrit :


I have a proposal for when to choose between OO and RDB...


Why would you have to choose between both ? Why do you even imply
there's a need to choose between both ?

(snip dead-wrong stuff)


Well if you want to implement a software solution to a given problem
you need to make some decisions.

And ? I do write softwares, and most of them uses both an OO language
and a RDBMS.


Not entirely sure what the issue is.

You said "most" (but not all). Therefore decisions have been made, or
did you just toss a coin?

Instead of trying to be funny, please take some time to understand the implications of the fact that there exist applications that are written using the OO paradigm *and* uses a RDBMS. One of these implications is that OO and RDBMS are *not* mutually exclusive. Which makes your "proposition" useless and irrelevant.

Isn't a more formal criteria useful? My aim is to come to a deeper
understanding of why OO has not displaced RM in certain domains.

Because OO is a general purpose programming paradigm, and RDBMS are systems to manage relational data. Apples and oranges.

It
mostly seems to be in Business domains, where we need to store
information *about* things.

OO is not about "storing" anything - it's about how to design a *program*. RDBMS are about efficient management (organisation, querying and storage) of *data*. Apples and oranges...

OO dominates lots of other domains like
image processing or GUI development.

Behaviour. You don't 'store' GUIs nor image processing. Apples and oranges.

I don't believe the need for persistence is the answer.

It's only part of it. We also need to enforce data coherence, handle concurrent access and atomic complex updates - and of course have a quick, reliable and flexible way to retrieve data. And - for most 'business' apps, to share them between different applications, most of the time written in different languages, and quite commonly running on different machines. RDBMS do have limitations, but there's still the best tools I know for such use case.

It is more
subtle than that.

RDBMS are about managing relational data. As the name implies... I don't see anything particularly "subtle" here.

Now I have another question for you : why RM has not displaced other data management tools in certain domains ?
.