From: Dan Nelson
Date: October 23 2001 3:14pm
Subject: Re: Length limit of 500 on primary keys?
List-Archive: http://lists.mysql.com/mysql/88859
Message-Id: <20011023101427.B26805@dan.emsphone.com>
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In the last episode (Oct 23), Jeremy Zawodny said:
> On Mon, Oct 22, 2001 at 11:42:23AM -0600, Steve Meyers wrote:
> > If you use a good 64-bit hash, I doubt you'll run into any
> > uniqueness problems.  MySQL will support that as a 64-bit BIGINT.
> > You especially should not have any problems if you hash each column,
> > then do the primary key across the four hashes.
> 
> Good to know.  I wonder how many collisions I'd find if I ran it over
> every URL listed in the directory www.yahoo.com.
> 
> Which 64 bit hash function did you use?  Invent your own, or something
> "off the shelf"?

I use md5.  128 bits (use the first 64 if that's all you need), and
there's a mysql builtin so if you're using a language that doesn't have
an MD5 routine, you can still generate the hash.

-- 
	Dan Nelson
	dnelson@stripped