Hierarchical Data Storage

[Trevor DeVore]

On Feb 13, 2007, at 2:38 AM, Ruslan Zasukhin wrote:

> What you mean with:
>
> * "forced everyone to update their lessons" ?
>
> So few users work with own lessons.
> Work via cursors, right?

Yes.

> Each cursors most probably will set at least READ lock.
> So yes, one user cannot update right nodes until other lock them.

Using the design in the article, Yes.

> Wait. No.
>
> If keep TreeID field, then will be
>
>     UPDATE .. WHERE treeid = rootID and left > x and right < y
>
> So USER1 will not touch trees of other users.

That is where the idea for the double came in.  You could keep the  
treeid in the number to the left of the decimal and the left/right  
value to the right.  But a treeid would work as well which kind of  
makes it a hybrid of the two hierarchal structures discussed, no?


-- 
Trevor DeVore
Blue Mango Learning Systems - www.bluemangolearning.com
trevor at bluemangolearning.com