Re: Object-relational impedence
Date: Wed, 05 Mar 2008 17:58:30 +0000
Message-ID: <fqmn0b$l6m$1_at_aioe.org>
Tegiri Nenashi wrote:
> On Mar 5, 9:31 am, S Perryman <q..._at_q.net> wrote:
>>Marshall wrote:
>>>Object oriented languages work in object-at-a-time terms.
>>>Even when those objects are collections, if one wants to
>>>operate on every object in the collection, one iterates
>>>over the objects in the collection and calls methods on
>>>those objects one at a time.
>>>The relational model works in set-at-a-time terms. One
>>>operates on entire sets at once.
>>This is a fallacy.
>>In any system, if I have a set S of tuples (x,y) , and request the
>>following :
>>I have to examine each tuple in the set to find those that satisfy the
>>predicate. The satisfying tuples do not appear by magic.
> Sigh: "magic optimization" (this is indeed a legitimate technical > term) is not applied in this case. However, consider an index on > column x.
Sigh : in the text "{ e IN S : e.x = 123 }" there is no "index" . Merely a Relational expression.
The use of index is an *implementation* technique.
Argue about implementation techniques as much as you want. But you cannot claim that all OO prog langs will have an implementation that forces the fallacious "one at a time" scheme (Functional programming being a case in point) .
Regards,
Steven Perryman
Received on Wed Mar 05 2008 - 18:58:30 CET