[SOLR-9501] Collapse filter should sometimes be cacheable instead of never

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: David Smiley
• Created: 11/Sep/16 20:18
• Updated: 08/Jun/19 15:31

Description

When SolrIndexSearcher.getDocSet(List<Query>queries) is called, it first checks if any implement the marker interface ScoreFilter, and if so it calls out to getDocSetScore[1] instead of continuing. CollapsingPostFilter is the only Query implementing ScoreFilter. There is a presumption here that any CollapsingPostFilter needs the score. But this just isn't true; you can collapse with a min/max/sort on something that doesn't need the score. So there is a needless performance hit here.

[1] I don't like that getDocSetScore presumes the first query in the list is the scoring one – it's a poor API contract relationship; at a minimum the javadocs should be updated. This holds for getDocSet as well since it passes through. Perhaps getDocSet could be modified to take a nullable scoring Query first arg.

Issue Links

• is related to: SOLR-5416 CollapsingQParserPlugin breaks Tag/Exclude Faceting
• is related to: SOLR-9494 CollapseQParserPlugin doesn't propagate needsScores() correctly