[GitHub] [lucene] gsmiller commented on pull request #11738: Optimize MultiTermQueryConstantScoreWrapper for case when a term matches all docs in a segment.

[GitBox <gi...@apache.org>]

gsmiller commented on PR #11738:
URL: https://github.com/apache/lucene/pull/11738#issuecomment-1240856191

   @jpountz:
   
   > It might not be a big win in practice, but it should be enough to compare the docFreq with the docCount (rather than maxDoc) and use this postings whose docFreq is equal to docCount as an iterator of matches.
   
   I like that idea. I wonder if checking for both conditions makes sense? If a term contains all docs in the segment, it should be more efficient to use `DocIdSet#all` right? (rather than iterating the actual postings). But, if a term doesn't contain all docs in the segment but _does_ contain all docs in the field (i.e., the field isn't completely dense), we could add an additional optimization here to use that single term's postings. Is that what you had in mind?
   
   Here's what I'm thinking:
   ```
             int docFreq = termsEnum.docFreq();
             if (reader.maxDoc() == docFreq) {
               return new WeightOrDocIdSet(DocIdSet.all(docFreq));
             } else if (terms.getDocCount() == docFreq) {
               TermStates termStates = new TermStates(searcher.getTopReaderContext());
               termStates.register(termsEnum.termState(), context.ord, docFreq, termsEnum.totalTermFreq());
               Query q = new ConstantScoreQuery(new TermQuery(new Term(query.field, term), termStates));
               Weight weight = searcher.rewrite(q).createWeight(searcher, scoreMode, score());
               return new WeightOrDocIdSet(weight);
             }
   ```


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