Re: Re: Mapping output from a SEQUENCE into something non-repeating/colliding but random-looking?

On May 1, 2009, at 6:06 AM, Craig Ringer wrote:

<snip>

> What I'm looking for is a function that, given an input within a
> constrained range (say, a 32 bit integer) produces a different output
> within the same range. For any given input, the output should be the
> same each time, and for any given output there should only be one
> input
> that results in that output.

I think you drop the idea of a repeatable mapping you may have some
success with the Knuth (aka Fisher-Yates) shuffle algorithm:  http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

   Why does anything need to be repeatable when you only need to make
sure that each number is only generated once?

Erik Jones, Database Administrator
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