Solr: Retrieve field names from a solr index?

Question

How can I query a Solr instance for all (or prefixed) field names?

I want to use dynamic fields where I do not know how many may exist e.g: category_0_s,

Answer 1

Use the luke handler:

http://solr:8983/solr/admin/luke?numTerms=0

Use a xpath to get all the field which has the tag dynamicBase matching the dynamic fields definition you are looking for.