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https://issues.apache.org/jira/browse/JCR-1213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12545796
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Ard Schrijvers commented on JCR-1213:
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Hello Marcel,
just read your patch. I'll try to test your solution tomorrow at the end of
the day as well. AFAICS, I think performance between both solutions won't be
measurable. Your code is nicer, as I already indicated I had some dependencies
I did not like at all.
When creating a lot of nodes, also remember to "update" a lot of nodes, to
create the 'gabs' in the index, and lots of parents that are found in
different indexes.
I never new about the creation tick. If it is unique for a reader instance, it
should obviously work. Also nice to not have the SingleTermDocs dependance in
UUIDDocId! Anyway, I'll check your patch tomorrow, and think we have a very
much better working cache here for the hierarchical relations.
> UUIDDocId cache does not work properly because of weakReferences in
> combination with new instance for combined indexreader
> ---------------------------------------------------------------------------------------------------------------------------
>
> Key: JCR-1213
> URL: https://issues.apache.org/jira/browse/JCR-1213
> Project: Jackrabbit
> Issue Type: Improvement
> Components: query
> Affects Versions: 1.3.3
> Reporter: Ard Schrijvers
> Fix For: 1.4
>
> Attachments: JCR-1213-mreutegg.patch, JCR-1213.patch
>
>
> Queries that use ChildAxisQuery or DescendantSelfAxisQuery make use of
> getParent() functions to know wether the parents are correct and if the
> result is allowed. The getParent() is called recursively for every hit, and
> can become very expensive. Hence, in DocId.UUIDDocId, the parents are cached.
> Currently, docId.UUIDDocId's are cached by having a WeakRefence to the
> CombinedIndexReader, but, this CombinedIndexReader is recreated all the time,
> implying that a gc() is allowed to remove the 'expensive' cache.
> A much better solution is to not have a weakReference to the
> CombinedIndexReader, but to a reference of each indexreader segment. This
> means, that in getParent(int n) in SearchIndex the return
> return id.getDocumentNumber(this) needs to be replaced by return
> id.getDocumentNumber(subReaders[i]); and something similar in
> CachingMultiReader.
> That is all. Obviously, when a node/property is added/removed/changed, some
> parts of the cached DocId.UUIDDocId will be invalid, but mainly small indexes
> are updated frequently, which obviously are less expensive to recompute.
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