Re: Possible bridges between OO programming proponents and relational model

From: J M Davitt <jdavitt_at_aeneas.net>
Date: Sun, 04 Jun 2006 19:01:59 GMT
Message-ID: <H6Ggg.54099$P2.44569@tornado.ohiordc.rr.com>

Cimode wrote:
> J M Davitt wrote:
>

>>Cimode wrote:
>>
>>><<I am not certain I agree with that last sentence.>>Can you ellaborate
>>>on that? What
>>>do you have in mind?
>>>
>>><<That's a different issue.>>You really think so?  I would argue that
>>>it is too closely related to to be ignored.
>>>
>>><<However, that does not change the degree of a table and
>>> does not change the fact that the degree is a direct measure of the
>>> dimensions.>>  Yes.  So.  I have never denied that.  This is why I
>>>made a distinction between SQL tables as they are implemented and SQL
>>>tables as they should be represented.  Do you have any idea onto how an
>>>in memory SQL table footprint looks like on current SQL DBMS?
>>
>>Clarification please: are you saying that direct image implementations
>>are two dimensional because all the columns are adjacent to each other
>>in a row?  (If so, you're writing a very different language than the
>>readers of your posts are reading.)
>>
>>[snip]

>
>
> <<Clarification please: are you saying that direct image
> implementations
> are two dimensional because all the columns are adjacent to each other
> in a row? (If so, you're writing a very different language than the
> readers of your posts are reading.) >>
> Not only and the fact that they are adjacent is not really the issue
> but this description seems closer to what I mean. Thank you very much
> for helping a better formulation of the issue. (I may have troubles
> expressing the concept). This thread seems to be taking off after all.
> What is your insight on that.? Can OO in-memory mechanisms be helpful
> on that matter? Most people here seem to believe the opposite.
>

A couple points: although many SQL implementations are direct image - meaning that rows are stored as rows and tables are stored as tables - not all of them are. In other words, there are implementations where a table's rows and a row's columns are "spread out all over the place." This has nothing to do with either the relational model or SQL.

As for "OO in-memory mechanisms," I think that such storage schemes should be described a one-dimensional, don't you?. After all, each instance is allocated a bunch of bits from a linear address space. Just because it's apparently a simple matter to pass an address around doesn't mean that the content of all addresses are easily accessed. MIPS chips and Intel chips have very different techniques for managing large memory fields. But that fact doesn't have anything to do with OO concepts, does it? Well, neither does the choice of storage technique have anything to do with relational concepts or SQL. Received on Sun Jun 04 2006 - 14:01:59 CDT