CREATE EVENT TRIGGER CREATE EVENT TRIGGER 7 SQL - Language Statements CREATE EVENT TRIGGER define a new event trigger CREATE EVENT TRIGGER name ON event [ WHEN filter_variable IN (filter_value [, ... ]) [ AND ... ] ] EXECUTE { FUNCTION | PROCEDURE } function_name() 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 . The user who creates an event trigger becomes its owner. 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 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. Only superusers can create event triggers. Event triggers are disabled in single-user mode (see ) as well as when is set to false. If an erroneous event trigger disables the database so much that you can't even drop the trigger, restart with set to false to temporarily disable event triggers, or in single-user mode, and you'll be able to do that. 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(); There is no CREATE EVENT TRIGGER statement in the SQL standard.