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https://issues.apache.org/jira/browse/JCRVLT-53?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14053521#comment-14053521
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Thomas Mueller commented on JCRVLT-53:
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> My patch still improves performance about 20-fold (for Oak) and 10-fold (for
> Jackrabbit 2.x), so I think it's worth it.
Yes, in VLT, and after Jukka's improvement. Jukkas improvement is very good,
but it only addresses Oak (not Jackrabbit 2.x), and it can't possibly get to
the same performance as when not calling orderBefore at all.
I think it's also important to fix this in VLT because in the future, we expect
even flatter hierarchies. In which case trying to avoid orderBefore is even
more important (my test case is "just" 10'000 child nodes). I also expect other
people will try to re-use the algorithm from VLT for slightly different use
cases (using VLT code as the "gold standard"). So it is important that VLT uses
the most optimal solution.
> vlt: with many child nodes, NodeNameList.restoreOrder is very slow with Oak
> ---------------------------------------------------------------------------
>
> Key: JCRVLT-53
> URL: https://issues.apache.org/jira/browse/JCRVLT-53
> Project: Jackrabbit FileVault
> Issue Type: Improvement
> Reporter: Thomas Mueller
> Assignee: Thomas Mueller
> Attachments: JCR-3793.patch, ReorderTest.java
>
>
> The method org.apache.jackrabbit.vault.fs.api.NodeNameList.restoreOrder
> re-orders orderable child nodes by using Node.orderBefore. This is very slow
> if there are many child nodes, specially with Oak (minutes for 10'000 nodes,
> while only about 1 second for Jackrabbit 2.x).
> [~tripod], I wonder if a possible solution is to first check whether
> re-ordering is needed? For example using:
> {noformat}
> boolean isOrdered(ArrayList<String> names, Node parent)
> throws RepositoryException {
> NodeIterator it1 = parent.getNodes();
> for (Iterator<String> it2 = names.iterator(); it2.hasNext();) {
> if (!it1.hasNext() ||
> !it1.nextNode().getName().equals(it2.next())) {
> return false;
> }
> }
> return !it1.hasNext();
> }
> {noformat}
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