Hierarchical Data Storage

[Trevor DeVore]

On Feb 13, 2007, at 1:30 AM, Ruslan Zasukhin wrote:

> On 13/2/07 12:24 AM, "Bart Pietercil" <bart.pietercil at gmail.com>  
> wrote:
>
> Bart,
>
> Actually Trevor points that IF exists several ROOTs than this  
> algorithm
> simply may not work.
>
> Because you already cannot use
>     UPDATE WHERE  left > 1 and RIGHT < 32
>
> Because this UPDATE also will touch nodes of OTHER trees.
>
> Right Trevor?
>
> Hmm.

Well, I don't know that it won't work.  It seems that it would work  
as long as the left/right values for the each root node were set to  
it's children but there may be a complication.

My main concern is that editing one hierarchy in the table would  
invalidate the hierarchy information of records to the right of the  
node being updated.  In the example I presented, you could have  
multiple people working on different lessons at once.  If an update  
to the hierarchy in one lesson forced everyone to update their  
lessons that would be bad.


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