[LUCENE-3328] Specialize BooleanQuery if all clauses are TermQueries

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4, 4.0-ALPHA
• Fix Version/s: 4.0-ALPHA
• Component/s: core/search
• Lucene Fields: New, Patch Available
• Assignee: Simon Willnauer
• Reporter: Simon Willnauer
• Created: 20/Jul/11 10:40
• Updated: 28/Aug/22 12:53
• Resolved: 22/Jul/11 16:08

Description

During work on LUCENE-3319 I ran into issues with BooleanQuery compared to PhraseQuery in the exact case. If I disable scoring on PhraseQuery and bypass the position matching, essentially doing a conjunction match, ExactPhraseScorer beats plain boolean scorer by 40% which is a sizeable gain. I converted a ConjunctionScorer to use DocsEnum directly but still didn't get all the 40% from PhraseQuery. Yet, it turned out with further optimizations this gets very close to PhraseQuery. The biggest gain here came from converting the hand crafted loop in ConjunctionScorer#doNext to a for loop which seems to be less confusing to hotspot. In this particular case I think code specialization makes lots of sense since BQ with TQ is by far one of the most common queries.

I will upload a patch shortly