Re: teaching relational basics to people, questions
Date: 21 Nov 2009 19:12:28 GMT
Sampo Syreeni wrote:
>variable precision would be available at least at the conceptual
>level. At the physical one, it could always be implemented so that the
>complexity if bounded by the less precise of the compared values, or
>in fact limited to some fixed value at physical design time.
The most common types of database values can be represented in constant space and compared in constant time. For other types such as stringsor blobs of arbitrary size at least comparison is linear in the size of the values. In your proposal, the values are *arbitrary* reals. For all we know, they may be represented by algorithms to compute them - in which case comparing them may be pretty expensive - or even worse, they may be uncomputable. You'll need to constrain them at least to the extent that comparing them becomes a decidable problem.
>one would have to have a bona fide range datatype, building in
>handling for infinite ranges would also be easy; that'd get rid of one
>of the most persistent reasons why people incorporate nulls into
Yes, I agree with your basic idea, but I really think you want to replace 'arbitrary real number' with 'arbitrary precision integer' or 'arbitrary precision integer quotient' or something similar. They are similar to the strings and blobs we already have.
-- ReinierReceived on Sat Nov 21 2009 - 20:12:28 CET