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

event

filter_variable

filter_value

function_name

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))