List keys of a hashmap in range (key_start, key_end].
("", ""] means no range limit.
name - The name of the hashmapkey_start - The lower bound(not included) of keys to be returned, empty string means -inf(no limit).key_end - The upper bound(inclusive) of keys to be returned, empty string means +inf(no limit).limit - Up to that many elements will be returned.Key list.
The key list is return as: k1 k2 ...
ssdb 127.0.0.1:8888> hgetall h
key             value
-------------------------
  a               : a
  b               : b
  c               : c
  d               : d
  e               : e
  f               : f
6 result(s) (0.000 sec)
ssdb 127.0.0.1:8888> hkeys h a c 10
			  key
-----------------
				b
				c
2 result(s) (0.000 sec)
ssdb 127.0.0.1:8888>