作者
digoal
日期
2021-04-14
标签
PostgreSQL , failsafe vacuum SKIP heap truncate
背景
PG 14 为了防止xid wraparound的情况, 支持了强制vacuum 加速的功能
新增一个patch, 在使用强制加速vacuum时, 跳过heap truncate(例如末尾的全部为空的block正常可以被truncate, 但是truncate会改变文件大小, 可能还涉及inode更新, 锁等更多的额外动作, 与强制加速的理念违背, 所以PG 14 又补了一个patch, 跳过heap truncate.)
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=60f1f09ff44308667ef6c72fbafd68235e55ae27
```
Don't truncate heap when VACUUM's failsafe is in effect.
author Peter Geoghegan pg@bowt.ie
Tue, 13 Apr 2021 19:58:31 +0000 (12:58 -0700)
committer Peter Geoghegan pg@bowt.ie
Tue, 13 Apr 2021 19:58:31 +0000 (12:58 -0700)
commit 60f1f09ff44308667ef6c72fbafd68235e55ae27
tree b292538abf7696415e2df9aed2019d5777f70285 tree
parent 6c0373ab77359c94b279c4e67c91aa623841af65 commit | diff
Don't truncate heap when VACUUM's failsafe is in effect.
It seems like a good idea to bypass heap truncation when the wraparound
failsafe mechanism (which was added in commit 1e55e7d1) is in effect.
Deliberately don't bypass heap truncation in the INDEX_CLEANUP=off case,
even though it is similar to the failsafe case. There is already a
separate reloption (and related VACUUM parameter) for that.
Reported-By: Masahiko Sawada sawada.mshk@gmail.com
Discussion: https://postgr.es/m/CAD21AoDWRh6oTN5T8wa+cpZUVpHXET8BJ8Da7WHVHpwkPP6KLg@mail.gmail.com
```
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