Re: Object-relational impedence

From: Christopher Browne <cbbrowne_at_acm.org>
Date: Sun, 16 Mar 2008 21:53:08 -0400
Message-ID: <87hcf6w1yz.fsf_at_wolfe.cbbrowne.com>


Martha Stewart called it a Good Thing when Robert Martin <unclebob_at_objectmentor.com> wrote:
> On 2008-03-12 10:11:54 -0500, topmind <topmind_at_technologist.com> said:
>> You "downplay" RDBMS.
>
> Over the years I have learned to do that a lot less. There was a time
> that I considered DBs to be "a bucket of bits". Thanks, in part, to
> these crossposted discussions between c.o and c.d.t I have come to
> have a very different opinion.
>
>> You compared queries to "assembler language" in
>> one reply, for example. While not a direct "attack" it is the next
>> nearest thing.
>
> I can undertand why someone might take offense at that, if one
> thought that there was something awful about assembly language.

The comparison suggests that SQL is a low level language like assembler. I can see this being regarded as offensive...

> The real point of that remark was that the user of a tool is at a
> higher level of abstraction than the tool itself. SQL is a tool.
> ORMs are tools that use SQL to get their job done, just like compilers
> use assembly to get their job done. In that sense ORMs live at a
> higher level of abstraction than SQL.

The trouble is, I haven't seen any O/R mapping systems that have seemed particularly good. The most frequent approach, of basically tying object attributes fairly primitively to table data is one that loses entirely the SQL abilities surrounding set processing and aggregation or aggregate processing.

> The members of c.d.t. might respond negatively to that idea because
> they see SQL as a better vehicle to do the job that the ORM is
> trying to do. That's fine, but does not change the fact that the ORM
> is using SQL as an implementation language.

It tends to lead to losing SQL capabilities, which seems rather a loss...

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Received on Mon Mar 17 2008 - 02:53:08 CET

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