On Thu, Jul 06, 2006 at 10:16:42PM +1200, David Clarke wrote:
> column that is calculated from another column in the table but I think
> it would still be more effective than a serial id.
There is the problem that the hash is not proved unique (in fact,
someone has generated collisions on md5). Primary keys have to be
unique, of course.
I _think_ with a hundred columns, you could probably prove (using
brute force, if need be) that the hashes are going to be unique,
assuming the list of possible values in each column is bounded.
A
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