Re: 4 the FAQ: Are Commercial DBMS Truly Relational?

Christopher Browne <cbbrowne_at_acm.org> wrote:

[snip]

>The notion of "wrong answers with good performance" can also fit with
>the notion of using approximations.
>
>There are cases where modelling the exact correct result is costly,
>and that an approximation will suffice at lower cost.

     In which case, the approximation is a correct answer.

>There are numerous sorts of costs:
>
> - CPU usage
> - I/O usage
> - The amount of time and skill required to generate the report
>
>An approximate answer that takes an hour to find that is "close
>enough" that allows timely decision making is better than one that is
>exact but that took too long to find so that the information arrived
>too late for use.

     I define correct in this sense as being per the spec. If the spec allows for an approximation, such an answer is correct.

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:

     I have preferences.
     You have biases.
     He/She has prejudices.