类型: | integer |
默认: | 200000000 |
最低限度: | 100000 |
最大: | 2000000000 |
上下文: | postmaster |
重新开始: | true |
指定在一个VACUUM操作被强制执行来防止表中事务ID回卷之前,一个表的pg_class.relfrozenxid域能保持的最大年龄(事务的)。注意即便自动清理被禁用,系统也将发起自动清理进程来阻止回卷。
清理也允许从pg_xact子目录中移除旧文件,这也是为什么默认值被设置为较低的2亿事务。该参数只能在服务器启动时设置,但是对于个别表可以通过修改表存储参数来降低该设置。详见vacuum-for-wraparound。
建议 [EN]
Triggers autovacuum automatically if a table is about to suffer from XID rollover. The setting is very conservative, and should probably be increased to 500million, but not higher.
在 StackOverflow
在 pgsql-hackers
- Overhauling "Routine Vacuuming" docs, particularly its handling of freezing
- Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode
- RE: Some shared memory chunks are allocated even if related processes won't start
- How to stop autovacuum silently
- Re: Overhauling "Routine Vacuuming" docs, particularly its handling of freezing