Re: Parameters from trigger to function. - Mailing list pgsql-general

From Tom Lane
Subject Re: Parameters from trigger to function.
Date
Msg-id 26953.1087966910@sss.pgh.pa.us
Whole thread Raw
In response to Parameters from trigger to function.  (Vams <vmudrageda@charter.net>)
List pgsql-general
Vams <vmudrageda@charter.net> writes:
> CREATE OR REPLACE FUNCTION id_protect(text) RETURNS TRIGGER AS '
> ...
> CREATE TRIGGER protector BEFORE INSERT OR UPDATE ON testing FOR EACH ROW
> EXECUTE PROCEDURE id_protect('testing_id_seq');

> ERROR:  function id_protect() does not exist

> Now, why am I getting that error?

Trigger functions *never* take any normal parameters.

You can put parameters into the CREATE TRIGGER command, but they are
passed via a different mechanism (in plpgsql, it's an array called
tg_argv[]).  This is a bit weird but I think it goes along well with
the fact that triggers get a whole bunch of parameters, and from time
to time we add some.  We could not do that without breaking every
existing user trigger if the parameters were all to be declared as
explicit function parameters.

See http://www.postgresql.org/docs/7.4/static/plpgsql-trigger.html
for more ...

            regards, tom lane

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