Question

my problem is easy to explain with an example: I have a ‘common’ schema (the public one?) where I store common data between a clustered application.

For every instance of my application, I have a role (used as the application user).
And i have a common role, app_users, with read-only privileges on the common schema, and every application role is a member of app_users.

Now my problem is: how can i set a trigger on the app_a scheme that execute a function (procedure) in the common scheme, but affect the (and only the) app_a tables?

I mean:

// common_scheme, dummy function to emulate the mysql on update = now()
CREATE OR REPLACEFUNCTION update_etime() RETURNS TRIGGER AS $$
    BEGIN 
    NEW.etime = date_part('epoch'::text, now())::int;
    RETURN NEW;
    END;
$$ language plpgsql;

// now, in the app_foo scheme, i have the table:
CREATE TABLE foo_table (fid serial not null primary key unique, label char(25));
// and the trigger:
CREATE TRIGGER foo_table_update_etime BEFORE UPDATE ON foo_talbe FOR EACH ROW EXECUTE PROCEDURE update_etime();
// ERROR:  function update_etime() does not exist
CREATE TRIGGER foo_table_update_etime BEFORE UPDATE ON foo_talbe FOR EACH ROW EXECUTE PROCEDURE common_scheme.update_etime();
// ERROR:  function common_scheme.update_etime() does not exist

The user that will access app_foo has the execute privilege on update_etime() function in common_schema.

Any idea?

I’ve googled around but the only solution I fount to call functions from other schemas is something like execute 'select * from ' || schema_name || '.table_name'; but i dont think this will do the trick in my case, becose the function must work with the ‘local’ scheme.

Answer 1

Your second set of syntax should work… the one with “EXECUTE PROCEDURE common_scheme.update_etime();“

If it isn’t finding the function, I’d guess that you either have created it in a different schema than you think it is in, or you haven’t created it at all (and note, your example create syntax has a bug, no space between “replace” and “function”, which would cause an error when trying to create the function. Try doing a:

\df *.update_etime

As superuser to verify the function exists and is in the location you think it is in. HTH.