how to create event trigger for create table or select into

Question

i want create event trigger for create table or select into, eg: when create table xxxx must table name bigen with 'temp'

my code

    CREATE OR REPLACE FUNCTION create_table_func()
    RETURNS event_trigger
    AS
    $$
    DECLARE
          V_TABLE name := TG_TABLE_NAME;

BEGIN

    if V_TABLE !~ '^temp'

    then

      RAISE EXCEPTION 'must bigen with temp';

    end if;

END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

CREATE EVENT TRIGGER create_table_1 ON ddl_command_start

WHEN TAG IN ('SELECT INTO')

EXECUTE PROCEDURE create_table_func();

but when execute select * into test11 from test_bak

[Err] ERROR: column "tg_table_name" does not exist

Mccormack

Answer 1

The special variable TG_TABLE_NAME is only supported in normal triggers, not in event triggers (there is not always an associated table!).

The documentation has a list of functions that can return context information in an event trigger.

You could use pg_event_trigger_ddl_commands() to get the information you need, but that only works in ddl_command_end event triggers. That should work for you; I don't see a reason why the trigger should not run at the end of the statement.

Pelisse

Answer 2

this is my code ,it's meet my needs

code:

CREATE OR REPLACE FUNCTION trg_create_table_func()
RETURNS event_trigger
LANGUAGE plpgsql
AS $$
DECLARE
    obj record;    
BEGIN
  FOR obj IN SELECT * FROM pg_event_trigger_ddl_commands() WHERE command_tag in ('SELECT INTO','CREATE TABLE','CREATE TABLE AS')
  LOOP
        if   obj.object_identity !~ 'public.temp_'  
        THEN
        raise EXCEPTION 'The table name must begin with temp_';
        end if;
        END LOOP;
END;
$$;

CREATE EVENT TRIGGER trg_create_table ON ddl_command_end
WHEN TAG IN ('SELECT INTO','CREATE TABLE','CREATE TABLE AS')
EXECUTE PROCEDURE trg_create_table_func();

out recods

[Err] ERROR: The table name must begin with temp_ CONTEXT: PL/pgSQL function trg_create_table_func() line 10 at RAISE

it's cool ~

Mccormack