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

[kdotsky at gmail.com]

kdot... at gmail.com wrote:
> 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?
>

I just realized that of course the hash is not always going to be
unique, so this wouldn't really work.  And it seems a hash table would
still need to store the keys (as strings) so that string comparisons
can be done when a collision occurs.  I guess there's no avoiding
storing they keys?