Adrien Grand created LUCENE-6047:
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Summary: Speed up prohibited clauses when they produce an
oal.util.BitSet
Key: LUCENE-6047
URL: https://issues.apache.org/jira/browse/LUCENE-6047
Project: Lucene - Core
Issue Type: Improvement
Reporter: Adrien Grand
Priority: Minor
When we have a query that has a required clause A and an prohibited clause B (A
AND_NOT B), we typically use A's iterator to drive the iteration and then check
B's iterator to see if it also has the document.
Yet we have a couple of queries (eg. MultiTermQuery with filter rewrite) and
filters (eg. TermsFilter) that fill an oal.util.BitSet in order to return an
iterator, and this BitSet could return its inverse iterator quite efficiently
by using {{nextClearBit}} instead of {{nextSetBit}} to locate the next document.
This would potentially make queries that have prohibited clauses faster by
performing a leap-frog instead of running the positive clauses first and then
checking the negative clauses afterwards?
This could also be a way for BooleanQuery to be faster when the cost of the
optional/required clauses is high by loading the DocIdSetIterators of the
prohibited clauses into a BitSet and turning the inverse of the BitSet (using
nextClearBit instead of nextSetBit) into a required clause? This would
typically be used by Solr when running pure negative queries (see
QueryUtils.fixNegativeQuery) which are made of a required clause on a
MatchAllDocsQuery and a prohibited clause.
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