Nice one v. Always good to see different implementations. My first
impressions below.
As the author of DBIx::Class::Tree::NestedSet I tried to ensure that it
contained the same method names where possible as other similar modules
(such as DBIx::Class::Tree::AjacencyList).
I note you use the term 'ascendants' which is not a real word and so
would be confusing. Is this the same as 'ancestors'? If so then it would
be best to use ancestors since that is a word know by other people and
it keeps it consistent with other similar modules.
I have not had the chance to read the article or the code in detail, but
does this method allow the children to be ordered?
If so then you should also provide methods
left_siblings
right_siblings
left_sibling
right_sibling
leftmost_sibling
rightmost_sibling
etc. (see DBIx::Class::Tree::NestedSet for a full list)
Think about people who may want to port from one tree implementation to
another. Having the same methods makes it much easier for someone to do
this if they find they don't have exactly the right algorithm.
Regards
Ian
On 03/08/2010 17:26, vdg wrote:
Hello all,
I have implemented a new dbic component to manage trees.
It's an alternative method to DBIx::Class::Tree::AdjacencyList and
DBIx::Class::Tree::NestedSet.
Basically it's the implementation of the general method describe in this
paper :
http://arxiv.org/pdf/cs.DB/0402051
with this model, you keep the advantage of NestedSet to query
descendants without difficulties querying ancestors.
Plus the encoding is not volatile (no need to recalculate half of the
tree encoding after an insert) and there is
a direct correspondence between the materialized path of a node and its
encoding. The model is described in the paper
are more scalable, but i've yet to make some tests to get an idea how
deep you can build down in a tree.
This implementation don't use at all the primary key of the table (if
any) and don't try to order children.
Ordered tree could be a sub component i guess.
The only trade-off is that i use 7 (!) columns to do the encoding.
github : http://github.com/vdg/DBIx-Class-Tree-Fast
Comments and ideas very welcome off course.
v.
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