Just as the title asks...
I'm using doc_values where ever possible. But I have a query that specifies specific fields to return rather then the full source.
Are those fields loaded in fieldata cache?
It will, so that it can do the query on them. But as fas as I understand it won't load into fielddata cache, it'll just load them to read them and then eventually age out with GC.
Ok let me check closer, cause I switched to doc_values and I got field_data cache growing. I may have missed a field or it may be a non doc_value field
Unless you have everything as docvalues, wjhich can only be done on unanalysed fields, you will still get fielddata cache growth.