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https://issues.apache.org/jira/browse/LUCENE-7619?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16506535#comment-16506535
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David Smiley commented on LUCENE-7619:
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RE TokenStreamToAutomaton and finalOffsetGapAsHole, shouldn't this be ignored
when preservePositionIncrements==false? In other words, I think
finalOffsetGapAsHole should only have an effect when preservePositionIncrements.
> Add WordDelimiterGraphFilter
> ----------------------------
>
> Key: LUCENE-7619
> URL: https://issues.apache.org/jira/browse/LUCENE-7619
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Major
> Fix For: 6.5, 7.0
>
> Attachments: LUCENE-7619.patch, LUCENE-7619.patch, LUCENE-7619.patch,
> after.png, before.png
>
>
> Currently, {{WordDelimiterFilter}} doesn't try to set the {{posLen}}
> attribute and so it creates graphs like this:
> !before.png!
> but with this patch (still a work in progress) it creates this graph instead:
> !after.png!
> This means (today) positional queries when using WDF at search time are
> buggy, but since we fixed LUCENE-7603, with this change here you should be
> able to use positional queries with WDGF.
> I'm also trying to produce holes properly (removes logic from the current WDF
> that swallows a hole when whole token is just delimiters).
> Surprisingly, it's actually quite easy to tweak WDF to create a graph (unlike
> e.g. {{SynonymGraphFilter}}) because it's already creating the necessary new
> positions, and its output graph never has side paths, except for single
> tokens that skip nodes because they have {{posLen > 1}}. I.e. the only fix
> to make, I think, is to set {{posLen}} properly. And it really helps that it
> does its own "new token buffering + sorting" already.
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