Re: Navigation question
Date: 17 Feb 2007 03:13:37 -0800
On Feb 17, 1:19 am, "Marshall" <marshall.spi..._at_gmail.com> wrote:
> 'Tis a theory newsgroup. It's enough that the optimization I describe
> be implementable; it doesn't need to be actually implemented.
I don't think you made it clear enough that that part of your post contained a significant piece of conjecture. You said :
> Here's a possible execution scenario:
then described in real world detail, including caches and disks, how Dawn's two queries might be executed. You then said :
> my approach:
> 1) The system observes that they are both selects so it can order them
> at its pleasure. So it picks q2 first because it has contacts loaded in cache.
which can only, given what you said in your post above, be described as significant conjecture. Both Dawn and I took this to mean, in context, you knew of some DBMS that would optimize in this way. It would also be an awful "proof" of anything, given that the conjecture includes another conjecture, namely "it has contacts loaded in cache". How do you know ?
The benefits of set-based processing are such that it doesn't need conjectures or imaginings to show. The idea that you "navigate" in an SQL database (hierarchical queries excepted, of course) is plain wrong, and doesn't need conjectures or imaginings to show.
[ snippage ]
> However one could imagine, say, an asynchronous JDBC tag library that
> would permit this optimization.
And ? I can imagine lots of things too - the death of SQL or at least the removal of 'connect by' and friends; or the elimination of both NULL and 3VL; or proper support for user defined types, indexing and functions (better than PostgreSQL does it, anyway). I wouldn't use those imaginings to prove a point, at least not without significant health warnings.