Re: Possible bridges between OO programming proponents and relational model
Date: 3 Jun 2006 07:37:48 -0700
Message-ID: <1149345468.467215.176680_at_f6g2000cwb.googlegroups.com>
Cimode wrote:
>
> Second, I make a clear distinction between SQL tables *as implemented
> currently* and relvars (called also R-tables). On that standpoint, I
> do not see how are current *physical* implementations of SQL are
> multidimensional when all the ones I know (but I only know the main
> exposed above) use direct image storage of tuple physical
> implementation.(totally defeating relational independence between
> logical and physical layer).
Okay; you're discussing the physical layer here. (Although your parenthetical remark is incorrect; the choice of a particular implementation strategy isn't what determines whether you have independence or not.)
> So I am curious to why, presicely you are
> saying that a SQL table is multidimensional.
Whoops! Now you're talking about the logical layer.
As Bob already said, a relation with N attributes is n-dimensional. This is true regardless of whether you implement that relation with a row store or a column store or a piggy bank of slips of paper. This is by definition.
> My guess is that you are
> refering to what SQL should be as opposed as to how it is implemented.
> On that case, I agree with that statement. On the opposite case
Not really; the reference is to the logical layer rather than the physical layer. There's no "should be" here; that's how it is.
> Third, the hidden agenda of this thread is to focus discussion on
> in-memory logic projection of relvars assuming total independence
> between disk based storage and representation of R-Tables at runtime.
> As you also know current SQL implementations (and SQL implemented
> tables) are direct projection of physically static (generally
> bidimensional) representation of tuples.
No, I don't think that's correct at all. Physical memory is
unidimensional;
everything else is a layer on top of that.
> On such perspective, the
> little education I have about OO mechanisms encourages me to seek
> discussion with OO audience to educate myself about possibilities OO
> can offer to drive a better relational implementation.
Well, I wouldn't do that if I were you. I think your best bet is to study the existing literature on relational implementation. Read ten papers and see if you think OO has something useful to say.
Marshall Received on Sat Jun 03 2006 - 16:37:48 CEST