Incorrect sort by Numeric (double) values for documents missing the sorting
field
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Key: LUCENE-3390
URL: https://issues.apache.org/jira/browse/LUCENE-3390
Project: Lucene - Java
Issue Type: Bug
Components: core/search
Affects Versions: 3.3
Reporter: Gilad Barkai
Priority: Minor
While sorting results over a numeric double field, documents which do not
contain a value for the sorting field seem to get 0 (ZERO) value in the sort.
This behavior is unexpected, as zero is "comparable" to the rest of the values.
A better solution would either be allowing the user to define such a
"non-value" default, or always bring those document results as the last ones.
Example scenario:
Adding 3 documents, 1st with value 3.5d, 2nd with -10d, and 3rd without any
value.
Searching with MatchAllDocsQuery, with sort over that field in descending order
yields the docid results of 0, 2, 1.
Example code:
public static void main(String[] args) throws Exception {
RAMDirectory d = new RAMDirectory();
IndexWriter w = new IndexWriter(d, new
IndexWriterConfig(Version.LUCENE_33, new KeywordAnalyzer()));
// 1st doc, value 3.5d
Document doc = new Document();
doc.add(new NumericField("f", Store.YES, true).setDoubleValue(3.5d));
w.addDocument(doc);
// 2nd doc, value of -10d
doc = new Document();
doc.add(new NumericField("f", Store.YES, true).setDoubleValue(-10d));
w.addDocument(doc);
// 3rd doc, no value at all
w.addDocument(new Document());
w.close();
IndexSearcher s = new IndexSearcher(d);
Sort sort = new Sort(new SortField("f", SortField.DOUBLE, true));
TopDocs td = s.search(new MatchAllDocsQuery(), 10, sort);
for (ScoreDoc sd : td.scoreDocs) {
System.out.println(sd.doc + ": " + s.doc(sd.doc).get("f"));
}
s.close();
d.close();
}
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