Re: Navigation question

"Andy Dingley" <dingbat_at_codesmiths.com> wrote in message news:1171990396.924858.28580_at_p10g2000cwp.googlegroups.com...
> On 14 Feb, 19:47, "Marshall" <marshall.spi..._at_gmail.com> wrote:
>
> > select * from orders where date > '2006-01-01' and status =
> > 'fulfilled' and customerid = 1234
> >
> > You say what you want and you get just that. No sifting
> > through stuff you don't want; no navigating.
>
> Why is that good though? Because it avoids navigation, or because it
> avoids round-tripping?
> IMHO it's avoiding the second thhat is the advantage here, not the
> first
>
Neither of the above. It's good because it does not require the inquirer to know about anything other than the data.

"Navigation" as commonly used around here, means following "paths" between the data. If the inquirer has to navigate, the inquirer has to know about the available paths. Not having to know that stuff is an advantage. It's an advantage for several reasons. One of them is, possibly, performance. But this isn't the big reason. The big reason is independence.

If the inquirer expresses the query in language that makes the query's results dependent on the avilability of certain navigational paths, then a modification to the data structure can render that query invalid. That's not good. Received on Tue Feb 20 2007 - 18:57:49 CET