[jira] [Created] (LUCENE-7541) FVH does not work well with phrases and multiple tags

["David Pilato (JIRA)" <ji...@apache.org>]

David Pilato created LUCENE-7541:
------------------------------------

             Summary: FVH does not work well with phrases and multiple tags
                 Key: LUCENE-7541
                 URL: https://issues.apache.org/jira/browse/LUCENE-7541
             Project: Lucene - Core
          Issue Type: Bug
          Components: modules/highlighter
    Affects Versions: trunk, 6.x
            Reporter: David Pilato
         Attachments: Add_test_for_FVH_with_phrase_and_multiple_tags_.patch

I'm indexing a document with a field which is {{aaa bbb ccc ddd bbb eee fff}}.

I'm running a Bool Query which contains 2 should Phrase queries: {{aaa bbb}} and {{eee fff}}.

I'm using an FVH with two tags {{<1></1>}} and {{<2></2>}}.

It gives the correct result: {{<1>aaa bbb</1> ccc ddd bbb <2>eee fff</2>}}

With same settings, I'm now running with 2 should Phrase queries: {{aaa bbb}} and {{bbb eee}}.

I'm getting back a wrong result: {{<1>aaa bbb</1> ccc ddd <1>bbb eee</1> fff}} where I'm expecting {{<1>aaa bbb</1> ccc ddd <2>bbb eee</2> fff}}.

Why this?

Apparently the FVH is getting back as sequence numbers in the first case {{0}} and {{1}} but in the second case {{0}} and {{2}}.

The problem is when we call then {{getPreTag}}, we are getting the first tag instead of the second one:

{{code:java}}
  protected String getPreTag( String[] preTags, int num ){
    int n = num % preTags.length;
    return preTags[n];
  }
  
  protected String getPostTag( String[] postTags, int num ){
    int n = num % postTags.length;
    return postTags[n];
  }
{{code:java}}

I did not find yet how to fix that. But I believe it is somewhere in {{org.apache.lucene.search.vectorhighlight.FieldQuery}} class

{{code:java}}
    private void markTerminal( int slop, float boost ){
      this.terminal = true;
      this.slop = slop;
      this.boost = boost;
      this.termOrPhraseNumber = fieldQuery.nextTermOrPhraseNumber();
    }
{{code:java}}

This call to {{nextTermOrPhraseNumber()}} increments the term number I guess because we have already seen the term {{BBB}} previously.

I'm going to join a test case patch.




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