Re: recursing down a tree

I did a little research on the subject and it seemed quite interesting.
However, it seemed that insertion would require updating most of the tree for
a minor insert. Can you send along a few more details about your setup and
algorithms? I would like to find more information about this.

Regards,
    Jeff

On Tuesday 02 July 2002 06:07 am, Fran Fabrizio wrote:
> Carl Meyer wrote:
> >hi,
> >
> >say i have a table with something like
> >
> >id,parent,description
>
> Depending on what your most common types of queries are, you might be
> better off with Joe Celko's nested set model (from the book SQL for
> Smarties).  It would do:
>
> id, left, right, description
>
> where you traverse the tree depth-first and as you pass the left side of
> each node you increment a counter (left) and as you pass by it again on
> the right you increment it again (right).
>
> This model provides much easier ways of making queries such as "give me
> all descendants of id=2" because there's then no recursion (WHERE
> child.left between parent.left and parent.right).
>
> I had a table set up exactly as you have described, and when the
> recursion proved too costly in terms of db performance, I went to nested
> set and we're pleased with the results.
>
> Just another option,
> Fran
>
>
>
>
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