Re: [Q] string to int hash function for small range

On Sat, Mar 07, 2009 at 09:33:33PM -0500, V S P wrote:
> I would like to have a function
> given a user id varchar(64) to get a hash number between 0 and 255.
>
> I first tried md5 but the number it returns is very big and cannot
> be converted to an INT
>
> there is likely a way to simply add ascii values of the userId together
> to get a small integer, but wanted to know if there are any other
> 'built-in' ways
>
> this is to get the database id based on user id.

this is bad idea, as there will be collisions. better use sequential
ids.

but if you *have to*:

select hashtext('username') % 128 + 127;

depesz;

--
Linkedin: http://www.linkedin.com/in/depesz / blog: http://www.depesz.com/
jid/gtalk: depesz(at)depesz(dot)com / aim:depeszhdl / skype:depesz_hdl / gg:6749007