[LUCENE-8347] BlendedInfixSuggester to handle multi term matches better

• Type: Improvement
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 7.3.1
• Component/s: core/search
• Lucene Fields: New, Patch Available
• Assignee: Unassigned
• Reporter: Alessandro Benedetti
• Created: 04/Jun/18 17:03
• Updated: 28/Aug/22 15:31

Description

Currently the blendedInfix suggester considers just the first match position when scoring a suggestion.
From the lucene-dev mailing list :
"
If I write more than one term in the query, let's say 
 
"Mini Bar Fridge" 
 
I would expect in the results something like (note that allTermsRequired=true and the schema weight field always returns 1000)
 

• Mini Bar Fridge something
• Mini Bar Fridge something else
• Mini Bar something Fridge        
• Mini Bar something else Fridge
• Mini something Bar Fridge
  ...
   
  Instead I see this: 
   
  - Mini Bar something Fridge        
  - Mini Bar something else Fridge
  - Mini Bar Fridge something
  - Mini Bar Fridge something else
  - Mini something Bar Fridge
  ...
   
  After having a look at the suggester code (BlendedInfixSuggester.createCoefficient), I see that the component takes in account only one position, which is the lowest position (among the three matching terms) within the term vector ("mini" in the example above) so all the suggestions above have the same weight 
  "
  Scope of this Jira issue is to improve the BlendedInfix to better manage those scenarios.

Issue Links

• requires: LUCENE-8343 BlendedInfixSuggester bad score calculus for certain suggestion weights
• links to: GitHub Pull Request #393