Hi,

I'd suggest going with option 1 from your original email.  It's the most
natural mapping of application data to JCR nodes.  For getting all answers
or all comments, I'd use a search query (very simple in SQL syntax:  Just do
"select * from my:answer").

Given what I've read about Jackrabbit performance on very large, flat (>5000
nodes as first-level children of a single node) node trees, I'd try to come
up with a way to group the my:questions nodes to avoid getting an overly
large set of children from a single my:qna node.

It also seems to me that using references to keep track of which comments
are associated with a given answer would be simulating the organization of
RDBMS tables.  Better, IMO, to keep it with a simple, easily-understood node
structure.

Hope this helps,

-Brian


On 3/21/07, alartin <alartin@gmail.com> wrote:
>
>
> Hi all,
>   I am trying to write a QnA (question and answer) demo of jackrabbit and
> have a few questions about Object and Content Mapping.
>   Given three objects: qeustion, answer, and comment. One question may has
> many answers and comments; one answer may have many comments. Answer and
> comment can not exist alone.
>   In OCM, I have two choice:
> 1. subnodes:
>             1 root -- 1 my:qna -- * my:question
>                                                     |__  * my:answer  ___
>                                                     |__  *
> my:comment    |__
> * my:comment
> 2. same level(use reference):
>             1 root -- 1 my:qna -- 1 my:questions
>                                                              |__ *
> my:question
>                                        -- 1 my:answers
>                                                              |__ *
> my:answer
>                                        -- 1 my:comments
>                                                                |__ *
> my:comment
>    I can use the multi-value property to store the references. For
> example,
> one my:question has a multi-value property named "answers" and each value
> is
> the uuid of one my:answer node and each my:answer hold the uuid of the
> question node.
> My question is : what's the difference between the two choice?
> If I need do a lot of access or calculating to answers or comments, is it
> better to choose the 2th choice? Thus, I do not need to iterate all
> questions to find all answers or comments.
> The second question is: Is it important to make a single my:questions
> node/my:answers node/my:comments node?
> If not, there are many different nodes in one level. Is it a big problem
> in
> the future such as searching performance?
> Many thanks!
> --
> View this message in context:
> http://www.nabble.com/Node-mapping-question%3A-when-should-I-use-subnode--tf3439621.html#a9590761
> Sent from the Jackrabbit - Users mailing list archive at Nabble.com.
>
>