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https://issues.apache.org/jira/browse/LUCENENET-612?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shad Storhaug resolved LUCENENET-612.
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Fix Version/s: Lucene.Net 4.8.0
Resolution: Fixed
This has now been resolved in Lucene.NET 4.8.0-beta00007
> SERIOUS issues with PerFieldAnalyzerWrapper in 4.8
> --------------------------------------------------
>
> Key: LUCENENET-612
> URL: https://issues.apache.org/jira/browse/LUCENENET-612
> Project: Lucene.Net
> Issue Type: Bug
> Components: Lucene.Net.Analysis.Common
> Affects Versions: Lucene.Net 4.8.0
> Reporter: Shad Storhaug
> Priority: Major
> Fix For: Lucene.Net 4.8.0
>
> Original Estimate: 16h
> Remaining Estimate: 16h
>
> This came in on the user mailing list on 15-July-2019 and was originally
> reported by Bryan Rojo ([email protected])
>
> {quote}Not necessarily a bug, but for some people who use
> PerFieldAnalyzerWrapper like I do this might be worth noting.
> PerFieldAnalyzerWrapper has been "improved" in 4.8 and now uses a
> PER_FIELD_REUSE_STRATEGY which means that the tokenized fields will be stored
> in a dictionary, so If you have multiple fields with the same name in your
> document, then you will only be able to index the very first one that makes
> it into that dictionary.
> So the problem with this is that you can potentially lose thousands of terms
> in your index, which could cause your searches to be of very low quality.
> BEWARE.
> {quote}
>
> There are 2 issues that need to be resolved to address this:
> 1. The documentation for {{PerFieldAnalyzerWrapper}} should be updated to
> inform users that if they need to use multiple dictionary keys with the same
> name, they should use {{TreeDictionary<K, V>}}.
> 2. {{TreeDictionary<K, V>}} does not currently implement
> {{System.Collections.Generic.IDictionary<TKey, TValue>}}, as it was brought
> over from C5 as-is.
> Another thing of note is that C5 has added support for .NET Standard 1.0
> since this was brought over.
> However, there still seems to be a few problems that make the C5 types
> incompatible with Lucene.Net, most notably the lack of support for
> {{System.Collections.Generic.IDictionary<TKey, TValue>}} in
> {{TreeDictionary}} and {{System.Collections.Generic.ISet<T>}} in {{TreeSet}}
> (the latter of which has already been patched in
> {{Lucene.Net.Support.TreeSet}}).
> I [reported|https://github.com/sestoft/C5/issues/53] the lack of support for
> {{ISet<T>}} on 6-Nov-2016, but although the maintainers agree this should be
> done, it still hasn't been. Perhaps a PR to the C5 project is the way to get
> this done, which would allow us to finally remove these collection copies
> from Lucene.Net.Support and add a package dependency on C5.
> Another option is to shop around to see if there are any other generic
> TreeSet/TreeDictionary implementations that have popped up since late 2016
> that we can check for compatibility.
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