Re: Natural keys vs Aritficial Keys

From: Walter Mitty <>
Date: Mon, 18 May 2009 17:20:18 GMT
Message-ID: <mNgQl.2102$>

"paul c" <> wrote in message news:CAgQl.28536$PH1.3994_at_edtnps82...
> --CELKO-- wrote:
>>>> Speaking of efficiency, composite primary keys have almost no effect,
>>>> if you get the indexes right. <<
>> Ever work with DBs that use hashing instead of tree indexes? Longer
>> keys are better because there is less chance of a hash collision.
>> There is also a lot of work being done on minimal perfect hashing
>> right now. This is going to be very important for VLDB because
>> unlike indexes, a hash requires only one probe.
> Every so often some crackpot claims to have discovered the perfect hash
> but bigger keys usually need bigger buckets to reduce collisions. It
> reminds me of the old joke about the guy who kept re-running his
> compression program in hopes of reducing the file's size to one byte.

Ha, ha!

My seven most used files are each one byte long, but you should see how long the other 1000 files are!

I can't help but wishing the Claude Shannon's work was not more well understood among software engineers. Received on Mon May 18 2009 - 19:20:18 CEST

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