heap_force_kill 在不檢查元組的情況下將“已用”行指標標記為“已死”。此函式的預期用途是強制刪除無法透過其他方式訪問的元組。例如

test=> select * from t1 where ctid = '(0, 1)';
ERROR:  could not access status of transaction 4007513275
DETAIL:  Could not open file "pg_xact/0EED": No such file or directory.

test=# select heap_force_kill('t1'::regclass, ARRAY['(0, 1)']::tid[]);
 heap_force_kill
-----------------

(1 row)

test=# select * from t1 where ctid = '(0, 1)';
(0 rows)

heap_force_freeze 在不檢查元組資料的情況下將元組標記為已凍結。此函式的預期用途是使由於可見性資訊損壞而無法訪問的元組變得可訪問，或者由於可見性資訊損壞而阻止表成功 vacuuming 的元組。例如

test=> vacuum t1;
ERROR:  found xmin 507 from before relfrozenxid 515
CONTEXT:  while scanning block 0 of relation "public.t1"

test=# select ctid from t1 where xmin = 507;
 ctid
-------
 (0,3)
(1 row)

test=# select heap_force_freeze('t1'::regclass, ARRAY['(0, 3)']::tid[]);
 heap_force_freeze
-------------------

(1 row)

test=# select ctid from t1 where xmin = 2;
 ctid
-------
 (0,3)
(1 row)