Обсуждение: How to drop an trigger

I've created quite a few foreign key constraints in the database that I
am currently working on, and now that I've altered the structure and
dropped a table that had a foreign key reference to a couple of other
tables, I need to get rid of those foreign keys (they weren't dropped
automagically with the table), as I get errors on trying to update those
tables.

Trouble is that the foreign keys show up in a schema dump as <unnamed>
triggers (AFAIK there is no other way to display foreign key
constraints) which I don't know how to drop. Here's an example:

\connect - frank
--
-- TOC Entry ID 56 (OID 52367)
--
-- Name: "RI_ConstraintTrigger_52366" Type: TRIGGER Owner: frank
--

CREATE CONSTRAINT TRIGGER "<unnamed>" AFTER DELETE ON "index"  NOT
DEFERRABLE INITIALLY IMMEDIATE FOR EACH ROW EXECUTE PROCEDURE
"RI_FKey_cascade_del" ('<unnamed>', 'legende', 'index', 'UNSPECIFIED',
'platz', 'id');

I tried dropping it with 

=# drop trigger RI_ConstraintTrigger_52366 on index;

which fails with

ERROR:  DropTrigger: there is no trigger ri_constrainttrigger_52366 on
relation index

What to do? And more broadly, what's the recommended way to deal with
this in general? Avoid creating <unnamed> triggers by always creating named
foreign keys with something like

ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address)
REFERENCES addresses(address) MATCH FULL;

(from Bruce's book)?

Regards, Frank

On Thu, Mar 08, 2001 at 04:42:46PM +0100, Frank Joerdens wrote:
> I've created quite a few foreign key constraints in the database that I
> am currently working on, and now that I've altered the structure and
> dropped a table that had a foreign key reference to a couple of other
> tables, I need to get rid of those foreign keys (they weren't dropped
> automagically with the table), as I get errors on trying to update those
> tables.

Just an idea: Is it safe to just delete the corresponding row in
pg_trigger?

Regards, Frank

On Thu, Mar 08, 2001 at 05:06:29PM +0100, Frank Joerdens wrote:
> On Thu, Mar 08, 2001 at 04:42:46PM +0100, Frank Joerdens wrote:
> > I've created quite a few foreign key constraints in the database that I
> > am currently working on, and now that I've altered the structure and
> > dropped a table that had a foreign key reference to a couple of other
> > tables, I need to get rid of those foreign keys (they weren't dropped
> > automagically with the table), as I get errors on trying to update those
> > tables.
> 
> Just an idea: Is it safe to just delete the corresponding row in
> pg_trigger?

No, it ain't: After deleting the rows corresponding to the offending
triggers in pg_trigger, I can't vacuum, or dump.

- Frank

Frank Joerdens <frank@joerdens.de> writes:
>> Just an idea: Is it safe to just delete the corresponding row in
>> pg_trigger?

> No, it ain't: After deleting the rows corresponding to the offending
> triggers in pg_trigger, I can't vacuum, or dump.

You need to adjust the reltriggers counts in the associated pg_class
entries, too.
        regards, tom lane