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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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