a question on python dict

[Tim Peters]

[Tim Peters]
>>>> You should also note that copying a dict key or value (no matter of
>>>> what type) consists in its entirety of copying one machine address (a
>>>> 4- or 8-byte pointer, depending on platform).

[Lawrence D'Oliveiro]
>>> Actually, no. It also consists of updating reference counts as well.

[Tim Peters]
>> Not in context:  dict resizing is refcount-neutral...

[Lawrence D'Oliveiro]
> The question wasn't about resizing, it was about "copying a dict key or
> value".

Then you misunderstood the OP.  He was asking about dict resizing:

    ...

    When there are more and more items being added to the
    hashtable, it increase its buckets and copy the old items into the
    new one and re-calculate the hash value of each item.
    
    I think this will waste some time doing the increasing-copying
    thing.

Taking my response out of context to begin with doesn't really change that 
I answered the question he asked ;-)