heap_force_kill 将 “已使用” 的行指针标记为 “已失效”，而不检查元组。此函数的预期用途是强制删除其他无法访问的元组。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 将元组标记为已冻结，而不检查元组数据。此函数的预期用途是使由于损坏的可见性信息而无法访问的元组，或由于损坏的可见性信息而阻止表成功清理的元组可访问。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)