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

[Nick Vatamaniuc]

It should be enough but it might be a little slower than hash(string).

Diez B. Roggisch wrote:
> kdotsky 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.
>
> python dictionaries are "traditional" hash-tables.
>
> > 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.
>
> You could try and create a md5 sum of your strings and use that as key. It
> _should_ be good enough, but I'm no crypto expert so take that with a grain
> of salt.
> 
> Diez