Re: Improving CREATE CONSTRAINT TRIGGER documentation - trigger firing order

Tom Lane wrote:

Michael Glaesemann <grzm@seespotcode.net> writes: 

On Apr 21, 2007, at 4:39 , David Pufer wrote:   

In my opinion it would be nice to mention in SQL reference commands that
constraint triggers created by CREATE CONSTRAINT TRIGGER are fired in
creation order unlike regular triggers created by command CREATE
TRIGGER. As I know, the firing order of the CONSTRAINT TRIGGER is
determined by the XXXXX num at "RI_ConstraintTrigger_XXXXX" column in
pg_trigger table.     

I believe this just falls out of the normal order of trigger firing  
as explained in the CREATE TRIGGER documentation (http:// 
www.postgresql.org/docs/8.2/interactive/sql-createtrigger.html)   

The proposed change is wrong anyway: AFAICS from looking at the code,
an RI_ConstraintTrigger_XXXXX name is only generated for triggers that
are created in support of FOREIGN KEY constraint syntax.  If you use
CREATE CONSTRAINT TRIGGER then the trigger name is whatever you say it
is.  I don't recall if it was always like that, but that's definitely
the behavior in CVS HEAD.

It would be a mistake to assume that FK constraint triggers are fired in
creation order anyway, since the lexical sorting of strings isn't the
same as numeric order (not to mention OID wraparound issues).
		regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?
              http://www.postgresql.org/docs/faq 

I tested in in 8.2.3 stable.
e.g. command

CREATE CONSTRAINT TRIGGER my_constraint_trigger_name
AFTER INSERT OR UPDATE OR DELETE
ON my_test_table
DEFERRABLE INITIALLY DEFERRED
FOR EACH ROW EXECUTE PROCEDURE my_test_procedure()

created a row with tgname "RI_ConstraintTrigger_28329" and tgconstrname "my_constraint_trigger_name" in system catalog in table pg_trigger, while creation of normal trigger (not constraint trigger) puts its name into tgname column. As Tom notedm a while ago it might be different in CVS HEAD and consequently in 8.3.

Thanks for helpful info
David Pufer