Re: Guessing?
Date: Sun, 25 May 2008 21:43:12 -0400
Message-ID: <RAo_j.2439$co7.778_at_nlpi066.nbdc.sbc.com>
"paul c" <toledobysea_at_ac.ooyah> wrote in message
news:xuk_j.165843$Cj7.9496_at_pd7urf2no...
> Brian Selzer wrote:
> ...
>> Well, that's just it. It has no consistent method for doing so. ...
>
>
> It does, I gave one, ie., apply, ie., distribute algebraically, the union
> to the base relations in the view expression, then apply whatever
> constraints the definition has. Works just as consistently for deletes to
> joins.
>
>
> If it just
>> guesses at the intent, 50% of the time it will guess wrong, and you'll
>> end up with garbage in the database. As a consequence, queries like,
>> "How many suppliers are west of the Mississippi?" will return the wrong
>> answer.
>> ...
>
>
> My whole point is that the dbms has no business guessing, just following
> orders. Why anybody would imagine a dumb pre-programmed logical machine
> can know human intentions can only be pathological mysticism. As they
> say, "don't believe everything you think".
>
>
>>
>> But again, it should not allow the update if it has to guess, because
>> inevitably, it will guess wrong at least some of the time and the
>> database will end up corrupt. That it has to guess is not a guess.
>> ...
>
>
> It is mysticism to think that a dbms that follows its own consistent rules
> is somehow guessing.