[jira] [Created] (OAK-10660) DocumentNodeStore: avoid repeated commits of :childOrder in branch commits

["Julian Reschke (Jira)" <ji...@apache.org>]

Julian Reschke created OAK-10660:
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             Summary: DocumentNodeStore: avoid repeated commits of :childOrder in branch commits
                 Key: OAK-10660
                 URL: https://issues.apache.org/jira/browse/OAK-10660
             Project: Jackrabbit Oak
          Issue Type: Improvement
          Components: documentmk
            Reporter: Julian Reschke
            Assignee: Julian Reschke


- While persisting the branch commits, we are persisting large :childOrder properties repeatedly. In practice, only the last value is needed, so the previous ones could be cleaned up.
 - We currently do not keep information about when (revision) and where (_id) we have set :childOrder.
 - The "clean" approach would be to maintain a map of _id/revision that tells us in which revision we last set :childOrder. That could be used to pair the setting of the new value with a removal of the previous one.
 - But we may be able to simplify that: just maintain a list of _all_ revisions that changed :childOrder, and any time we need to set a new value for :childOrder, nuke the entries for all of these revisions. This would be harmless because an extra REMOVE_MAP_ENTRY operation is essentially free, except fo ra small overhead in processing.



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