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CREATE EVENT TRIGGER(7)	 PostgreSQL 17.5 Documentation CREATE EVENT TRIGGER(7)

NAME
       CREATE_EVENT_TRIGGER - define a new event trigger

SYNOPSIS
       CREATE EVENT TRIGGER name
	   ON event
	   [ WHEN filter_variable IN (filter_value [, ... ]) [ AND ... ] ]
	   EXECUTE { FUNCTION |	PROCEDURE } function_name()

DESCRIPTION
       CREATE EVENT TRIGGER creates a new event	trigger. Whenever the
       designated event	occurs and the WHEN condition associated with the
       trigger,	if any,	is satisfied, the trigger function will	be executed.
       For a general introduction to event triggers, see Chapter 38. The user
       who creates an event trigger becomes its	owner.

PARAMETERS
       name
	   The name to give the	new trigger. This name must be unique within
	   the database.

       event
	   The name of the event that triggers a call to the given function.
	   See Section 38.1 for	more information on event names.

       filter_variable
	   The name of a variable used to filter events. This makes it
	   possible to restrict	the firing of the trigger to a subset of the
	   cases in which it is	supported. Currently the only supported
	   filter_variable is TAG.

       filter_value
	   A list of values for	the associated filter_variable for which the
	   trigger should fire.	For TAG, this means a list of command tags
	   (e.g., 'DROP	FUNCTION').

       function_name
	   A user-supplied function that is declared as	taking no argument and
	   returning type event_trigger.

	   In the syntax of CREATE EVENT TRIGGER, the keywords FUNCTION	and
	   PROCEDURE are equivalent, but the referenced	function must in any
	   case	be a function, not a procedure.	The use	of the keyword
	   PROCEDURE here is historical	and deprecated.

NOTES
       Only superusers can create event	triggers.

       Event triggers are disabled in single-user mode (see postgres(1)) as
       well as when event_triggers is set to false. If an erroneous event
       trigger disables	the database so	much that you can't even drop the
       trigger,	restart	with event_triggers set	to false to temporarily
       disable event triggers, or in single-user mode, and you'll be able to
       do that.

EXAMPLES
       Forbid the execution of any DDL command:

	   CREATE OR REPLACE FUNCTION abort_any_command()
	     RETURNS event_trigger
	    LANGUAGE plpgsql
	     AS	$$
	   BEGIN
	     RAISE EXCEPTION 'command %	is disabled', tg_tag;
	   END;
	   $$;

	   CREATE EVENT	TRIGGER	abort_ddl ON ddl_command_start
	      EXECUTE FUNCTION abort_any_command();

COMPATIBILITY
       There is	no CREATE EVENT	TRIGGER	statement in the SQL standard.

SEE ALSO
       ALTER EVENT TRIGGER (ALTER_EVENT_TRIGGER(7)), DROP EVENT	TRIGGER
       (DROP_EVENT_TRIGGER(7)),	CREATE FUNCTION	(CREATE_FUNCTION(7))

PostgreSQL 17.5			     2025	       CREATE EVENT TRIGGER(7)

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