Precedence of stored vs docValues in solr

Question

If I have set both stored=true and docValues=true for a given field as follows,

what would be the precedence chosen by solr? As in, is it like, if I am doing a sort/facet operation on the id field, the value will be retrieved from docValues and if I am executing a normal search query which returns id field, it will be returned from stored field ?

Please help me to clarify this.

Answer 1

stored values aren't used for anything other than returning the value to the client - ie what value was submitted for the field when it was sent to Solr. So yes, if you perform a search (or anything that results in a document being returned to the client), the stored value is read and returned.

docValues implements an actual feature in Lucene that makes certain operations more effective (such as sorting and faceting as you've mentioned). They're a lower level feature, and you don't really "see" the underlying stored docvalues.

I'm guessing you're confusing these values since there's support for "use doc values as stored value"; in certain cases the value stored in a docvalue will be the same as the same as what the user submitted (for example for integer fields), so if Lucene has already read and used the docvalue - and it is compatible with the stored value, you can tell it to skip fetching the stored value as well - saving a read.