What does the _val_: do in Solr and what is it for?

Question

I am new to Solr and I am trying to get my head around it. I can't for the life of me find any decent documentation for Solr. I've checked on the official page to see what _val_ does but it doesn't explain it well.

If someone can explain it here and give examples of how it's used that would be great!

Answer 1

_val_ is a hook provided by Solr for FunctionQuery. You can pass in a function to the query to manipulate the score of a document.

Ex:

_val_:"recip(rord(myfield),1,2,3)"

Refer here for the SolrQuerySyntax