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From "Michael Segel" <mse...@segel.com>
Subject RE: "generated by default" question
Date Thu, 15 Jun 2006 13:11:16 GMT


Don't they teach math in engineering anymore?

Lets try this one more time.

In 9.21, if N does exist, then N represents a solution set of potential

In your interpretation, you are *implicitly* adding an additional boundary
that the sequence returns the MIN(N) regardless of the overall

That is not part of the spec!

Thus, if you fail to insert a value in to an identity row and the failure is
due to the fact that the sequence returned a value that was in use, while
there were other values within the solution set N, it is a bug.

However, if you could guarantee that the MIN(N) will be a value such that
the will succeed then you will be ok.

Again, here's how trivial the solution is:

If you have a row to be inserted within a table that has an identity column,
and that row has a value X for the identity column...

If that insert is successful and if (X>CBV) then reassign CBV to be X or the
next non-negative integer larger than X such that it complies with the math
in 9.21 (Note: You have to account for INC when INC > 1)

This will always guarantee that if implemented properly, then you will
always have the correct value.

It's that simple.
So why doesn't anyone from IBM or SUN who sells support fix this bug?
HINT: You should be able to implement a fix and do some unit testing within
3 business days. (24 hours of coding time.) [Longer if you're not familiar
with the code.]

Note: The cost per transaction of implementing this solution is minimal. All
the necessary information should be in memory at the time of the insert.

But hey! What do I know?
Its not like I wrote the operating system of an embedded 6809 controller and
the initial application used to add Chlorine during the water purification
process used in major cities throughout the US .... ;-) 


[P.S. Ok, I did. The point being that if you write careless code, you run
the risk of doing harm to others. That is why you need to be careful when
you follow a spec.]

> > However, that does not mean that the implementation of the sequence
> > generator is compliant.
> That's exactly what it means. And that's my final word. I will not
> pursue this debate further.
> "OH, East is East, and West is West, and never the twain shall meet"
> (Rudyard Kipling)
> --
> Bernt Marius Johnsen, Database Technology Group,
> Staff Engineer, Technical Lead Derby/Java DB
> Sun Microsystems, Trondheim, Norway

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