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From Apache Wiki <wikidi...@apache.org>
Subject [Jackrabbit Wiki] Update of "Performance" by MichaelDürig
Date Thu, 16 Sep 2010 11:42:56 GMT
Dear Wiki user,

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The "Performance" page has been changed by MichaelDürig.


  A. The current internal Jackrabbit design is optimized for small to medium sized child node
sets, i.e. up to ~10k child nodes per node. Really large child node sets negatively affect
write performance.
  Please note that this is not a general issue of JCR but specific to Jackrabbit's current
internal persistence strategy - independent from the fact if you use a normal persistence
manager or a "bundle" persistence manager, albeit the latter one is recommended; see PersistenceManagerFAQ.
Each node contains the references to all its child nodes. This is a design decision inside
Jackrabbit to improve speed when using few child nodes. To improve performance, introduce
some extra-levels to your content model. This also helps humans to explore the repository
when using a browser tool. Typical solutions are to use some categories of the context of
your data or date folders, such as "2009/01/09".
+ From Jackrabbit 2.2 on there are some utility classes in the org.apache.jackrabbit.flat
package of the jcr-commons module for automatically arranging nodes in a B-Tree like manner
while maintaining a flat view. See JCR-2688.   
  == Q. I have many references to a single node and performance goes down. ==
  A. The current Jackrabbit design is not optimized for many nodes referencing a single node,
because for easy back-referencing in the JCR API all those references are stored in the target
node. Please note that many people don't recommend references in a content model anyway -
see for example DavidsModel, [[http://wiki.apache.org/jackrabbit/DavidsModel#head-ed794ec9f4f716b3e53548be6dd91b23e5dd3f3a|rule

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