Redis - SET overwriting other types - redis

Question

The following code example will be done/written via a Python REPL and the redis-cli.
Redis server v=2.8.4
Background: Storing a long-running key (hash) in a redis key-value store, then attempting to store another key (with the same name, but different type - string) in the same key-value store.
Code will come first, then question(s):
>>> import redis
>>> db = redis.Redis(
... host='127.0.0.1',
... port=6379,
... password='',
... db=3)
>>> db.hset("123456", "field1", True)
1
>>> db.type("123456")
b'hash'
>>> db.hgetall("123456")
{b'field1': b'True'}
>>> db.set("123456", "new-value")
True
>>> db.type("123456")
b'string'
>>> db.get("123456")
b'new-value'
You will first notice that the SET option overwrites the HSET. Now when I try to overwrite the SET with:
>>> db.lset("123456", "list1", "list1value")
Traceback (most recent call last):
...
redis.exceptions.ResponseError: WRONGTYPE Operation against a key holding the wrong kind of value
WRONGTYPE Operation against a key holding the wrong kind of value
OR replacing SET with the same HSET:
>>> db.hset("123456", "field1", True)
Traceback (most recent call last):
...
redis.exceptions.ResponseError: WRONGTYPE Operation against a key holding the wrong kind of value
WRONGTYPE Operation against a key holding the wrong kind of value
In order to make sure this isn't a redis-py flaw, I tested in the redis-cli:
127.0.0.1:6379> HSET 12345 "field" "value1"
(integer) 0
127.0.0.1:6379> TYPE 12345
hash
127.0.0.1:6379> SET 12345 "newvalue"
OK
127.0.0.1:6379> TYPE 12345
string
127.0.0.1:6379> HSET 12345 "field" "value1"
(error) WRONGTYPE Operation against a key holding the wrong kind of value
Questions:
1) Is this a flaw in Redis or is this actually how it is supposed to work?
2) If this is "how it is supposed to work", why can I not overwrite the SET type with others?
** Edit: As the person answering the question did not understand 3) .. I am editing it
3) Which other type, besides SET, can I use for storing a STRING in the structure (KEY, VALUE) where I can also have a HASH as (KEY, FIELD, VALUE) - where the key is same but of different TYPE(s)?
Eg. I want to do:
127.0.0.1:6379> HSET 12345 "field" "value1"
(integer) 0
127.0.0.1:6379> TYPE 12345
hash
127.0.0.1:6379> SOME-COMMAND 12345 "newvalue"
OK
So that I have 1 hash and 1 "other" type of the same "key" 12345

Answer 1

This is the designed behavior, the second sentence in SET's documentation is.
If key already holds a value, it is overwritten, regardless of its type.
No, only SET has that power, other commands will error when presented with the wrong type of value.
Sorry, not following you.