Re: Cascade Trigger Not Firing

I thought that might be the answer, but it's a pretty big hole when we're
using triggers for audit purposes on financial data.

I'm going to have to really look at all my BEFORE UPDATE triggers and make
sure we're not missing any more.

And I have to stop telling management that a trigger means we always know
when a value changes.

Thanks,
Judy

On Fri, Sep 13, 2019 at 2:08 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Judy Loomis <hoodie(dot)judy(at)gmail(dot)com> writes:
> > I have a trigger that updates a target column when some other columns
> > change.
> > There is another trigger on the target column to update another table
> (the
> > column can be changed in other ways besides the first trigger).
> > If I update the target column directly the expected trigger fires.
> > But if the 1st trigger changes the target column and it wasn't in the
> list
> > of updated columns, the 2nd trigger doesn't fire.
> > Is this expected behavior?
>
> Per the manual (NOTES section of the CREATE TRIGGER man page):
>
> A column-specific trigger (one defined using the UPDATE OF column_name
> syntax) will fire when any of its columns are listed as targets in the
> UPDATE command's SET list. It is possible for a column's value to
> change even when the trigger is not fired, because changes made to the
> row's contents by BEFORE UPDATE triggers are not
> considered. Conversely, a command such as UPDATE ... SET x = x ...
> will fire a trigger on column x, even though the column's value
> did not change.
>
> It's not really practical for trigger firings to depend on what other
> triggers did or might do --- you'd soon end up with circularities.
>
> regards, tom lane
>

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*Judy Loomis*
469.235.5839