[LUCENE-10606] Optimize hit collection of prefilter in KnnVectorQuery for BitSet backed queries

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 9.3
• Component/s: core/search
• Labels: performance
• Assignee: Unassigned
• Reporter: Kaival Parikh
• Created: 09/Jun/22 05:51
• Updated: 28/Aug/22 16:41
• Resolved: 27/Jun/22 07:25

Description

While working on this PR to add prefilter testing support, we saw that hit collection took a long time for BitSetIterator backed scorers (due to iteration over the entire underlying BitSet, and copying it into an internal one)

These BitSetIterators can be frequent (as they are used in LRUQueryCache), and bulk collection can be optimized with more knowledge of the underlying iterator

Issue Links

• links to: GitHub Pull Request #951