don't need dictionary's keys - hash table?

[kdotsky at gmail.com]

Hello,
I am using some very large dictionaries with keys that are long strings
(urls).  For a large dictionary these keys start to take up a
significant amount of memory.  I do not need access to these keys -- I
only need to be able to retrieve the value associated with a certain
key, so I do not want to have the keys stored in memory.  Could I just
hash() the url strings first and use the resulting integer as the key?
I think what I'm after here is more like a tradition hash table.  If I
do it this way am I going to get the memory savings I am after?  Will
the hash function always generate unique keys?  Also, would the same
technique work for a set?

Any other thoughts or considerations are appreciated.

Thank You.