Thread: MYSQL_FDW trigger BEFORE UPDATE changes to NEW on a col not in theupdate statement don't go through

Hi All,
 I was pleasantly surprised to see that triggers can be created on FDW tables. I'm running into a problem.

I create a trigger on an imported foreign table. In the procedure, I change the value of a column that is not in the triggering update statement. This change does not make it to the mysql side.

CREATE OR REPLACE FUNCTION aatrigger_up() returns trigger
AS $$
DECLARE
BEGINIF NOT(row_to_json(NEW)->'pgrti' is NULL) THEN	NEW.pgrti = 2000000000*random();END IF;       RAISE NOTICE 'aarigger_up %', row_to_json(NEW)::text; return NEW;

END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER aarigger_up BEFORE UPDATE ON mysql.users FOR EACH ROW EXECUTE PROCEDURE aarigger_up();
update mysql.users set email = 'admin@example.com' where id = 1;	

I can see that the value for pgrti is updated in the NOTICE in postgres. In mysql the value is not updated. If I add the target col to the statement it does go through

update mysql.users set email = 'admin@example.com', pgrti=0 where id = 1;	

 I need this to work to be able to detect CRUD coming from PG in a little deamon that calls pg_triggers for updates coming from mysqld; without a means to detect changes originating from pg the triggers would fire twice. Any idea where I'd change MYSQL_FDW to do this (also add fields that are updated in the trigger before firing off to mysql)?

Hi Francois,

On Wed, Apr 22, 2020 at 8:09 AM Francois Payette
<francoisp@netmosphere.net> wrote:
> I create a trigger on an imported foreign table. In the procedure, I change the value of a column that is not in the
triggeringupdate statement. This change does not make it to the mysql side.
 

I'm not an expert on mysql_fdw, so maybe I'm missing something, but I
think we had the same issue in postgres_fdw.  See this:


https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=8b6da83d162cb0ac9f6d21082727bbd45c972c53;hp=7dc6ae37def50b5344c157eee5e029a09359f8ee

Best regards,
Etsuro Fujita