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https://issues.apache.org/jira/browse/JCR-642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12738376#action_12738376
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Lars Trieloff commented on JCR-642:
-----------------------------------

Thomas, do I see it right that introducing "hidden" nodes would mean only small 
effort is required to change existing persistence managers? And if we only 
introduce
hidden nodes once we have more child nodes than we would put into a node in the 
B-Tree, there would be no performance impact for deep and thin trees, right?

> Support flat content hierarchies
> --------------------------------
>
>                 Key: JCR-642
>                 URL: https://issues.apache.org/jira/browse/JCR-642
>             Project: Jackrabbit Content Repository
>          Issue Type: Improvement
>          Components: jackrabbit-core
>            Reporter: Jukka Zitting
>
> The current best practice with Jackrabbit is to avoid flat content structures 
> due to performance concerns.
> These concerns are caused by the fact that the NodeState implementation 
> requires the list of child node names and identifiers to be available at all 
> times.  In fact many (all?) current persistence managers implement this 
> requirement by storing and loading this list as a part of the serialized node 
> state. When this list grows, the performance and memory overhead of managing 
> the list grows as well. As a side note, this also creates potential 
> consistency issues since the parent/child links are stored both within the 
> child list of the parent node and as the parent link of the child node.
> To solve this issue, I believe we need to break the tight bonding between the 
> node state and the list of child nodes. This will likely require major 
> refactoring of the Jackrabbit core, including breaking the NodeState and 
> PersistenceManager interfaces, so I don't expect a solution in near future. 
> However, we should start thinking about how to best do this, and at least be 
> concerned about building in any more assumptions about the list of child 
> nodes always being readily available.

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