how to get all the attributes names of records in couchdb

gistfile1.js

/* this mapreduce pair returns all the keys of the attribute hash from all records in the system */

/* the map function to return all the values of keys */
function(doc) {
  keys = {}
  for(key in doc) { 
    if (key != "_id" && key != "_rev") {
      keys[key] = 1
    }
  }
  emit(null, keys);
}

/* the reduce function to combine all the keys of the attribute hash in the values */
function(keys, values, rereduce) {
    result = {}
    for(hash_name in values) {
      hash = values[hash_name];
      // merge all the hashes together
      for(key in hash) {
        result[key] = hash[key];
      }
    }
    return result;
}