CREATE_EVENT_TRIGGER(7pg15)

💅 CREATE EVENT_TRIGGER — define a new event trigger

Ok so bestie, welcome to CREATE_EVENT_TRIGGER from the PostgreSQL 15.19 Documentation (manual page CREATE EVENT_TRIGGER(7), section 7pg15 — you're in the right place, iykyk 🫶). This is the glow-up where you teach your database to react to stuff happening. Main character energy fr.

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✨ SYNOPSIS ✨

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

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🌸 DESCRIPTION 🌸

CREATE EVENT TRIGGER makes a brand new event trigger. The way it works: whenever the designated event happens, and the WHEN condition attached to the trigger (if you even gave it one, no pressure) is satisfied, the trigger function gets executed. Slay. 💅

For the full general introduction to event triggers, go read Chapter 40 — that's the lore.

Also important: the user who creates an event trigger becomes its owner. Like, congrats, you're the parent now. 👑

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🎀 PARAMETERS 🎀

• name — the name you're giving your shiny new trigger. This name must be unique within the database (no duplicates, no "twin flame" situations, genuinely has to be one of a kind ✨).
• event — the name of the event that triggers a call to the given function. Section 40.1 has the full guest list of event names if you need it.
• filter_variable — the name of a variable you use to filter events. This is what lets you restrict the trigger so it only fires for a subset of the cases where it's supported (very picky, very demure). Currently the only supported filter_variable is TAG.
• filter_value — a list of values for the associated filter_variable that should make the trigger fire. For TAG, that means a list of command tags (e.g., 'DROP FUNCTION').
• function_name — a user-supplied function, declared as taking no argument and returning type event_trigger.

Real talk about the syntax though: in 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 PROCEDURE keyword here is purely historical and deprecated — so like, it works, but it's giving vintage in a bad way. 🙈

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⭐ NOTES ⭐

Only superusers can create event triggers. No exceptions, no loopholes. 💀

Event triggers are disabled in single-user mode (see postgres(1)). And here's the rescue plan if things go sideways: if an erroneous event trigger disables the database so much that you can't even drop the trigger, restart in single-user mode and you'll be able to do that. Crisis averted, bestie. 🧚

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🔥 EXAMPLES 🔥

Want to forbid the execution of any DDL command? Say less. This function + trigger combo does exactly that:

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();

Look at her. Iconic. 🌈

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🦋 COMPATIBILITY 🦋

There is no CREATE EVENT TRIGGER statement in the SQL standard. We're simply built different. 💅

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💜 SEE ALSO 💜

• ALTER EVENT TRIGGER (ALTER_EVENT_TRIGGER(7))
• DROP EVENT TRIGGER (DROP_EVENT_TRIGGER(7))
• CREATE FUNCTION (CREATE_FUNCTION(7))

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And that's the whole page, bestie — go forth and trigger responsibly. This masterpiece is brought to you by PostgreSQL 15.19, dated 2026, and this very manual page is CREATE EVENT_TRIGGER(7) — the <rainbow>PostgreSQL 15.19 Documentat</rainbow>... ok fine, the PostgreSQL 15.19 Documentation, 2026. Mwah. 😘🎀