The IndexInfoRequestHandler returns detailed field information for each field in the underlying Lucene index (not just the fields listed in schema.xml). Each field provides its corresponding schema type. The index information provided includes the maximum number of documents (including deleted/updated documents), number of documents (not including deleted documents), and the Lucene index version which changes when the index itself changes.

http://localhost:8983/solr/select?qt=indexinfo&wt=json&indent=on :

{
 "responseHeader":{
  "status":0,
  "QTime":5},
 "fields":{
  "includes":{"type":"text"},
  "cat":{"type":"text_ws"},
  "alphaNameSort":{"type":"alphaOnlySort"},
  "id":{"type":"string"},
  "text":{"type":"text"},
  "manu_exact":{"type":"string"},
  "features":{"type":"text"},
  "price":{"type":"sfloat"},
  "incubationdate_dt":{"type":"date"},
  "timestamp":{"type":"date"},
  "manu":{"type":"text"},
  "sku":{"type":"textTight"},
  "name":{"type":"text"},
  "nameSort":{"type":"string"},
  "popularity":{"type":"sint"},
  "inStock":{"type":"boolean"},
  "weight":{"type":"sfloat"}},
 "index":{
  "maxDoc":16,
  "numDocs":16,
  "version":1171044717502}}