RE: Need ideas for SQL join select to replace logical view

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: Wilt, Charles
>
> Not sure I agree with this.
>
> There's a difference between storing the same data in two places, and
> storing two separate pieces of data that happen to have the same value.

Sure, Charles, but these two pieces don't "happen" to have the same value.
The determining factor is whether one piece can be derived from another.
And in this case, the start of one event can most certainly be derived from
the end of the previous one.


> Actually, given that BETWEEN is inclusive as you pointed out, I'd
> considering setting this up so that
> the end time didn't match the next start time. Instead, the start time
> would be 1 mircosecond greater
> than the last end time.

And would still be derived from the previous end time, and thus would break
the normalization rules.  This stuff really isn't subject to interpretation.
You either are or aren't normalized, and putting the same piece of data (or
a derived piece) in another row breaks normalization, plain and simple.

And note that I'm not saying that "strategic denormalization" is necessarily
bad; as always, it's a business decision.

But in this case, ISAM works on the original data, without the extra field
and without the extra writes.  I think that blaming the database design when
SQL needs more data and more I/O is simply denying the facts, which in this
case are clearly that ISAM is better than SQL for this problem.

Is this horse dead yet?

Joe