[ 
http://issues.apache.org/jira/browse/LUCENE-693?page=comments#action_12444317 ] 
            
Peter Keegan commented on LUCENE-693:
-------------------------------------

Yonik,

I tried out your patch, but it causes an exception on some boolean queries.
This one occurred on a boolean query with 3 required terms:

java.lang.ArrayIndexOutOfBoundsException: 2147483647
    at org.apache.lucene.search.TermScorer.score(TermScorer.java:129)
    at org.apache.lucene.search.ConjunctionScorer.score(
ConjunctionScorer.java:97)
    at org.apache.lucene.search.BooleanScorer2$2.score(BooleanScorer2.java
:186)
    at org.apache.lucene.search.BooleanScorer2.score(BooleanScorer2.java
:318)
    at org.apache.lucene.search.BooleanScorer2.score(BooleanScorer2.java
:282)
    at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:132)
    at org.apache.lucene.search.Searcher.search(Searcher.java:116)
    at org.apache.lucene.search.Searcher.search(Searcher.java:95)

It looks like the doc id has the sentinel value (Integer.MAX_VALUE).
Note: one of the terms had no occurrences in the index.

Peter



> ConjunctionScorer - more tuneup
> -------------------------------
>
>                 Key: LUCENE-693
>                 URL: http://issues.apache.org/jira/browse/LUCENE-693
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Search
>    Affects Versions: 2.1
>         Environment: Windows Server 2003 x64, Java 1.6, pretty large index
>            Reporter: Peter Keegan
>         Attachments: conjunction.patch
>
>
> (See also: #LUCENE-443)
> I did some profile testing with the new ConjuctionScorer in 2.1 and 
> discovered a new bottleneck in ConjunctionScorer.sortScorers. The 
> java.utils.Arrays.sort method is cloning the Scorers array on every sort, 
> which is quite expensive on large indexes because of the size of the 'norms' 
> array within, and isn't necessary. 
> Here is one possible solution:
>   private void sortScorers() {
> // squeeze the array down for the sort
> //    if (length != scorers.length) {
> //      Scorer[] temps = new Scorer[length];
> //      System.arraycopy(scorers, 0, temps, 0, length);
> //      scorers = temps;
> //    }
>     insertionSort( scorers,length );
>     // note that this comparator is not consistent with equals!
> //    Arrays.sort(scorers, new Comparator() {         // sort the array
> //        public int compare(Object o1, Object o2) {
> //          return ((Scorer)o1).doc() - ((Scorer)o2).doc();
> //        }
> //      });
>   
>     first = 0;
>     last = length - 1;
>   }
>   private void insertionSort( Scorer[] scores, int len)
>   {
>       for (int i=0; i<len; i++) {
>           for (int j=i; j>0 && scores[j-1].doc() > scores[j].doc();j-- ) {
>               swap (scores, j, j-1);
>           }
>       }
>       return;
>   }
>   private void swap(Object[] x, int a, int b) {
>     Object t = x[a];
>     x[a] = x[b];
>     x[b] = t;
>   }
>  
> The squeezing of the array is no longer needed. 
> We also initialized the Scorers array to 8 (instead of 2) to avoid having to 
> grow the array for common queries, although this probably has less 
> performance impact.
> This change added about 3% to query throughput in my testing.
> Peter

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