Это можно сделать с помощью таблиц INFORMATION_SCHEMA, а также системного каталога.
http://www.alberton.info/postgresql_meta_info.html
Например,
Список последовательностей
SELECT relname
FROM pg_class
WHERE relkind = 'S'
AND relnamespace IN (
SELECT oid
FROM pg_namespace
WHERE nspname NOT LIKE 'pg_%'
AND nspname != 'information_schema'
);
Триггеры списка
SELECT trg.tgname AS trigger_name
FROM pg_trigger trg, pg_class tbl
WHERE trg.tgrelid = tbl.oid
AND tbl.relname !~ '^pg_';
-- or
SELECT tgname AS trigger_name
FROM pg_trigger
WHERE tgname !~ '^pg_';
-- with INFORMATION_SCHEMA:
SELECT DISTINCT trigger_name
FROM information_schema.triggers
WHERE trigger_schema NOT IN
('pg_catalog', 'information_schema');