[LUCENE-2287] Unexpected terms are highlighted within nested SpanQuery instances

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Won't Fix
• Affects Version/s: 2.9.1
• Fix Version/s: 7.3
• Component/s: modules/highlighter

Environment

Linux, Solaris, Windows

• Lucene Fields: New
• Assignee: David Smiley
• Reporter: Michael Goddard
• Created: 26/Feb/10 16:27
• Updated: 28/Aug/22 12:21
• Resolved: 11/Jan/18 04:30

Description

I haven't yet been able to resolve why I'm seeing spurious highlighting in nested SpanQuery instances. Briefly, the issue is illustrated by the second instance of "Lucene" being highlighted in the test below, when it doesn't satisfy the inner span. There's been some discussion about this on the java-dev list, and I'm opening this issue now because I have made some initial progress on this.

This new test, added to the HighlighterTest class in lucene_2_9_1, illustrates this:

/*

• Ref: http://www.lucidimagination.com/blog/2009/07/18/the-spanquery/
  */
  public void testHighlightingNestedSpans2() throws Exception {

String theText = "The Lucene was made by Doug Cutting and Lucene great Hadoop was"; // Problem
//String theText = "The Lucene was made by Doug Cutting and the great Hadoop was"; // Works okay

String fieldName = "SOME_FIELD_NAME";

SpanNearQuery spanNear = new SpanNearQuery(new SpanQuery[]

{ new SpanTermQuery(new Term(fieldName, "lucene")), new SpanTermQuery(new Term(fieldName, "doug")) }

, 5, true);

Query query = new SpanNearQuery(new SpanQuery[]

{ spanNear, new SpanTermQuery(new Term(fieldName, "hadoop")) }

, 4, true);

String expected = "The <B>Lucene</B> was made by <B>Doug</B> Cutting and Lucene great <B>Hadoop</B> was";
//String expected = "The <B>Lucene</B> was made by <B>Doug</B> Cutting and the great <B>Hadoop</B> was";

String observed = highlightField(query, fieldName, theText);
System.out.println("Expected: \"" + expected + "\n" + "Observed: \"" + observed);

assertEquals("Why is that second instance of the term \"Lucene\" highlighted?", expected, observed);
}

Is this an issue that's arisen before? I've been reading through the source to QueryScorer, WeightedSpanTerm, WeightedSpanTermExtractor, Spans, and NearSpansOrdered, but haven't found the solution yet. Initially, I thought that the extractWeightedSpanTerms method in WeightedSpanTermExtractor should be called on each clause of a SpanNearQuery or SpanOrQuery, but that didn't get me too far.

Issue Links

• is duplicated by: LUCENE-5455 Nested SpanNear queries lose positional highlights
• is duplicated by: LUCENE-8121 UnifiedHighlighter can highlight terms within SpanNear clauses at unmatched positions
• is duplicated by: LUCENE-6796 Some terms incorrectly highlighted in complex SpanQuery