Returns all fields in a hash.
HKEYS key
Returns all field names in the hash stored at key.
Array reply: a list of fields in the hash, or an empty list when the key does not exist.
O(N) where N is the size of the hash.
@hash @read @slow
127.0.0.1:6379> HSET myhash field1 "Hello"
(integer) 1
127.0.0.1:6379> HSET myhash field2 "World"
(integer) 1
127.0.0.1:6379> HKEYS myhash
1) "field1"
2) "field2"HDEL, HEXISTS, HEXPIRE, HEXPIREAT, HEXPIRETIME, HGET, HGETALL, HGETEX, HINCRBY, HINCRBYFLOAT, HLEN, HMGET, HMSET, HPERSIST, HPEXPIRE, HPEXPIREAT, HPEXPIRETIME, HPTTL, HRANDFIELD, HSCAN, HSET, HSETEX, HSETNX, HSTRLEN, HTTL, HVALS.