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https://issues.apache.org/jira/browse/LUCENE-4571?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13504180#comment-13504180
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Robert Muir commented on LUCENE-4571:
-------------------------------------

I like the ideas Stefan!

{quote}
Using BooleanScorer will probably only give improvement by a factor (in some 
cases), but also this scorers would still generate all these useless candidates.
{quote}

It might be hard to beat this one (which already supports minShouldMatch as a 
side effect of its coord computation anyway i think) in cases with
lots of terms because I feel like inevitably supporting advance() on the 
subscorers will result in more heap operations/cpu (at least when i messed 
around on paper it seemed this way).

In fact in some situations I think even this one should be used when there are 
mandatory clauses: in any case booleanweight should have better heuristics to 
decide, limited by what the collector can deal with.

Collectors that support out of order scoring today I think are likely a lot 
faster with these minShouldMatch types of queries than BooleanScorer2. Thats 
why i brought it up: it could be an easy win for e.g. solr users.

But when the number of terms is smallish and one is super-common, its silly we 
don't try to improve the BS2 impl to at least try to handle the worst case :) 

At least for the sake of simplicity (not necessarily performance) I still think 
it would be good to factor minshouldmatch behavior out of disjunctionsumscorer 
if we try to make it use advance() on subscorers.

                
> speedup disjunction with minShouldMatch 
> ----------------------------------------
>
>                 Key: LUCENE-4571
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4571
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/search
>    Affects Versions: 4.1
>            Reporter: Mikhail Khludnev
>
> even minShouldMatch is supplied to DisjunctionSumScorer it enumerates whole 
> disjunction, and verifies minShouldMatch condition [on every 
> doc|https://github.com/apache/lucene-solr/blob/trunk/lucene/core/src/java/org/apache/lucene/search/DisjunctionSumScorer.java#L70]:
> {code}
>   public int nextDoc() throws IOException {
>     assert doc != NO_MORE_DOCS;
>     while(true) {
>       while (subScorers[0].docID() == doc) {
>         if (subScorers[0].nextDoc() != NO_MORE_DOCS) {
>           heapAdjust(0);
>         } else {
>           heapRemoveRoot();
>           if (numScorers < minimumNrMatchers) {
>             return doc = NO_MORE_DOCS;
>           }
>         }
>       }
>       afterNext();
>       if (nrMatchers >= minimumNrMatchers) {
>         break;
>       }
>     }
>     
>     return doc;
>   }
> {code}
> [~spo] proposes (as well as I get it) to pop nrMatchers-1 scorers from the 
> heap first, and then push them back advancing behind that top doc. For me the 
> question no.1 is there a performance test for minShouldMatch constrained 
> disjunction. 

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