CREATE EVENT TRIGGER(7) PostgreSQL 18.6 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 introduc- tion to event triggers, see Chapter 38. The user who creates an event trig- ger 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 trig- ger 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 re- turning type event_trigger. In the syntax of CREATE EVENT TRIGGER, the keywords FUNCTION and PROCE- DURE 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 dis- ables 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 18.6 2026 CREATE EVENT TRIGGER(7)
NAME | SYNOPSIS | DESCRIPTION | PARAMETERS | NOTES | EXAMPLES | COMPATIBILITY | SEE ALSO
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