Subject Re[2]: [IBO] Re: Primary Key of Query set by Trigger
Author Helen Borrie (TeamIBO)
At 11:08 AM 05-04-02 +0200, Dieter wrote:

>So I must precise my question: Can I have a real atomic operation in
>FB without generators by using the transactions the right way?

Yes, you can: but it takes rather more than what you are doing in the
supplied code.

>Since the system will be used only by few users concurrently the problem
>will not
>be of high priority, but I want to do it well.

I want to reiterate Svein's comment: in attempting to implement one "idea
of atomicity" you are violating a more serious (and recognised) one: your
primary keys having "significance as data". This is asking for
trouble. If you need to maintain a series of numbers of which each number
must be accounted for, then DO NOT use this number in your keys. Keys
should provide structure and nothing else.

I recall at a database design seminar I attended once, the presenter
referred to your style of key as a Happy Wanderer. This was a humorous
reference to a German (?) song, whose chorus (in English) began:
"I love to go a-wandering,
My knapsack on my back..."

As he saw it, that song was really written about keys that had data meaning
added to them in a knapsack. As the key went on its journey, it picked
things up on the road and poked them in its knapsack. Of course, sometimes
the knapsack gets heavy, so something gets thrown out, to make room for
some more things in the knapsack. Eventually, the knapsack gets too heavy
to carry so it has to be abandoned. (His message there was: design your
keys atomic, no knapsack, no wandering!)

Helen Borrie (TeamIBO Support)

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