[SOLR-16646] Create a new function query operator isnan to verify if value is NaN

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: main (10.0), 9.2
• Component/s: query
• Labels: FunctionQuery operator
• Assignee: Kevin Risden
• Reporter: Gabriel Magno
• Created: 03/Feb/23 20:00
• Updated: 27/Mar/23 18:07
• Resolved: 06/Feb/23 17:55

Description

It would be useful to have a function query operator (e.g. `isnan`) to check rather a value is a float NaN (not a number).

Examples of use cases:

• Filtering out resulting documents having NaN in a certain field or expression
• Setting values and expressions according to the condition of a field/expression being NaN (`if(isnan(value),0,1)`)
• Replacing NaN by a default value (similar as a coalesce): `if(isnan(value),0,value)`

This function/operator is particularly important considering that the cosine similarity calculated by KNN queries with Dense Vectors might return a NaN on the score depending on the vectors. For an example of a query returning NaN in the response (with the films example):

http://localhost:8983/solr/films/select?fl=id%2C%24similarity&q=*%3A*&similarity=%7B!knn%20f%3Dfilm_vector%20topK%3D10000%7D[0.0%2C0.0%2C0.0%2C0.0%2C0.0%2C0.0%2C0.0%2C0.0%2C0.0%2C0.0]&sort=%24similarity%20desc

Issue Links

• links to: GitHub Pull Request #1331