[SOLR-12375] ScoreMode not always set correctly in Solr queries

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.1, 7.3.1
• Fix Version/s: 7.4
• Component/s: search
• Assignee: David Smiley
• Reporter: David Smiley
• Created: 18/May/18 16:02
• Updated: 08/Jun/19 15:10
• Resolved: 23/May/18 19:56

Description

A query can be informed that scores are not needed based on it's context/use, and some queries are able to operate more efficiently if it knows this up-front. This is about the ScoreMode enum.

I reviewed the use of ScoreMode.COMPLETE in Solr and I think we should make the following changes:

Solr filter queries (fq) are non-scoring. SolrIndexSearcher.getProcessedFilter will pass ScoreMode.COMPLETE when it ought to be COMPLETE_NO_SCORES to createWeight. This perf bug is only applicable when the filter query is not cached (either cache=false local-param or no filter cache). This error was made in LUCENE-6220 (Solr 5.1); at that time it was a boolean.

The /export handler (more specifically ExportQParserPlugin) is also affected; it's COMPLETE when it should always be COMPLETE_NO_SCORES. Also appears to be in error since Solr 5.1.

SolrIndexSearcher.getDocListAndSetNC ought to use TOP_SCORES to track the top-score to be more correct but it's a distinction without a difference since MultiCollector.wrap with the DocSetCollector will combine it with COMPLETE_NO_SCORES to conclude the result is COMPLETE.

Issue Links

• is related to: SOLR-12393 ExpandComponent only calculates the score of expanded docs when sorted by score