Re: 2 b4 update triggers, what is fire sequence?

So ......

    you're saying it's possible .....

;-)

"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:pan.2003.02.12.08.00.17.102428_at_yahoo.com.au...
> On Wed, 12 Feb 2003 01:55:08 +0000, Michael wrote:
>
> > and upgrades of the package will overwrite it. I know the docs say
> > the trigger firing is not necessarily in a particular order, BUT unless
> > you're going to tell me that they're intentionally randomizing it there
> > has to be a way to figure it out.
>
> There isn't, trust me. Not that I've seen the source code, so I can't
> tell you whether they *are* intentionally randomising it or not.
>
> But think about it (and here I'm going to simplify ludicrously): when an
> insert happens on a table with multiple before insert triggers, Oracle
> basically has to select from a data dictionary table to see what triggers
> actually exist: call it TRIG$ for the sake of argument (which it isn't,
> but it will do).
>
> Now, put yourself in the situation of selecting from *ANY* table: what
> order do the rows come out in. None. It's completely and utterly random,
> unless you throw in an ORDER BY clause. It depends on which blocks were on
> and off the freelist at the time of the inserts; who hit the ENTER key
> first, what blocks are already cached in the Buffer Cache, and in all
> probability on the wind speed and the size of the last prime number you
> thought of. There is NO order for returning rows from a heap table, unless
> you demand one.
>
> Guess what? Oracle itself doesn't demand one from TRIG$ (or whatever the
> real equivalent happens to be called these days).
>
> So it is random-ish. If you knew every possible variable, and could adjust
> for them, then you could probably predict the order of firing. But you
> don't, I don't, no-one does. So you can't.
>
> It's random. As random as a random thing can be, anyway.
>
> There's nothing to work out, nothing to test for, nothing to swing things
> a particular way.
>
> I like to think of it as a butterfly's wing, and the resulting logical
> corruptions to be the IT equivalent of a hurricane in Sussex.
>
> Chaotic, in other words.
>
> Regards
> HJR
>
Received on Wed Feb 12 2003 - 02:43:42 CST