Они прописываются в системной view pg_event_trigger
https://www.postgresql.org/docs/9.6/static/catalog...
В psql есть сокращение \dy выполняющее вот такой запрос:
SELECT evtname as "Name", evtevent as "Event", pg_catalog.pg_get_userbyid(e.evtowner) as "Owner",
case evtenabled when 'O' then 'enabled' when 'R' then 'replica' when 'A' then 'always' when 'D' then 'disabled' end as "Enabled",
e.evtfoid::pg_catalog.regproc as "Procedure", pg_catalog.array_to_string(array(select x from pg_catalog.unnest(evttags) as t(x)), ', ') as "Tags"
FROM pg_catalog.pg_event_trigger e ORDER BY 1