[jira] Commented: (LUCENE-1427) QueryWrapperFilter should not do scoring

["Paul Elschot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-1427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12641930#action_12641930 ] 

Paul Elschot commented on LUCENE-1427:
--------------------------------------

Indeed a simple win, but it can be even simpler (untested):
{code}
  return new DocIdSet() {
    public DocIdSetIterator iterator() {
      return scorer;
    }
  };
{code}
This DocIdSetIterator should be used only once, so it's best to cache it in a CachingWrapperFilter, and the javadocs could indicate that.

See also LUCENE-1296, which allows the choice of a supporting data structure other than OpenBitSet.

> QueryWrapperFilter should not do scoring
> ----------------------------------------
>
>                 Key: LUCENE-1427
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1427
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>            Priority: Minor
>             Fix For: 2.9
>
>
> The purpose of QueryWrapperFilter is to simply filter to include the docIDs that match the query.
> Its implementation is wasteful now because it computes scores for those matching docs even though the score is unused.  We could fix this by getting a Scorer and iterating through the docs without asking for the score:
> {code}
> Index: src/java/org/apache/lucene/search/QueryWrapperFilter.java
> ===================================================================
> --- src/java/org/apache/lucene/search/QueryWrapperFilter.java	(revision 707060)
> +++ src/java/org/apache/lucene/search/QueryWrapperFilter.java	(working copy)
> @@ -62,11 +62,9 @@
>    public DocIdSet getDocIdSet(IndexReader reader) throws IOException {
>      final OpenBitSet bits = new OpenBitSet(reader.maxDoc());
>  
> -    new IndexSearcher(reader).search(query, new HitCollector() {
> -      public final void collect(int doc, float score) {
> -        bits.set(doc);  // set bit for hit
> -      }
> -    });
> +    final Scorer scorer = query.weight(new IndexSearcher(reader)).scorer(reader);
> +    while(scorer.next())
> +      bits.set(scorer.doc());
>      return bits;
>    }
> {code}
> Maybe I'm missing something, but this seams like a simple win?

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