полный пример:
BEGIN;
DO $$
DECLARE
_cmd text;
_cursor CONSTANT refcursor := '_cursor';
BEGIN
SELECT string_agg(E'\n'||'select brin_summarize_new_values('''||ns.nspname||'.'||cls.relname||'''),'''||ns.nspname||'.'||cls.relname||''' as IndexName ',' union all ') INTO _cmd
FROM pg_index idx
JOIN pg_class cls ON cls.oid=idx.indexrelid
JOIN pg_class tab ON tab.oid=idx.indrelid
JOIN pg_catalog.pg_namespace AS ns ON tab.relnamespace = ns.oid
JOIN pg_am am ON am.oid=cls.relam
WHERE am.amname = 'brin';
--RAISE NOTICE 'SQLCMD: %', _cmd;
OPEN _cursor FOR EXECUTE _cmd;
END $$;
FETCH ALL FROM _cursor;