[LUCENE-9114] Add FunctionValues.cost

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 9.0
• Component/s: modules/query
• Lucene Fields: New
• Assignee: Atri Sharma
• Reporter: David Smiley
• Created: 06/Jan/20 02:52
• Updated: 28/Aug/22 15:55
• Resolved: 05/Mar/20 04:33

Description

The FunctionRangeQuery uses FunctionValues.getRangeScorer which returns a subclass of ValueSourceScorer. VSC's TwoPhaseIterator has a matchCost impl that returns a constant 100. This is pretty terrible; the cost should vary based on the complexity of the ValueSource provided to FRQ. ValueSource's are typically nested a number of levels, so they should aggregate.

BTW there is a parallel concern for FunctionMatchQuery which works with DoubleValuesSource which doesn't have a cost either, and unsurprisingly there is a TPI with matchCost 100 there.

Issue Links

• is related to: LUCENE-9373 Allow FunctionMatchQuery to customize matchCost of TwoPhaseIterator
• is required by: SOLR-14166 Use TwoPhaseIterator for non-cached filter queries
• links to: GitHub Pull Request #1303