Skip to content
体验新版
项目
组织
正在加载...
登录
切换导航
打开侧边栏
Greenplum
Gpdb
提交
5995953a
G
Gpdb
项目概览
Greenplum
/
Gpdb
通知
7
Star
1
Fork
0
代码
文件
提交
分支
Tags
贡献者
分支图
Diff
Issue
0
列表
看板
标记
里程碑
合并请求
0
DevOps
流水线
流水线任务
计划
Wiki
0
Wiki
分析
仓库
DevOps
项目成员
Pages
G
Gpdb
项目概览
项目概览
详情
发布
仓库
仓库
文件
提交
分支
标签
贡献者
分支图
比较
Issue
0
Issue
0
列表
看板
标记
里程碑
合并请求
0
合并请求
0
Pages
DevOps
DevOps
流水线
流水线任务
计划
分析
分析
仓库分析
DevOps
Wiki
0
Wiki
成员
成员
收起侧边栏
关闭侧边栏
动态
分支图
创建新Issue
流水线任务
提交
Issue看板
体验新版 GitCode,发现更多精彩内容 >>
提交
5995953a
编写于
9月 19, 1996
作者:
M
Marc G. Fournier
浏览文件
操作
浏览文件
下载
电子邮件补丁
差异文件
Documentation on the fsync() patch from OpenLink
Submitted by: Cees de Groot <C.deGroot@inter.nl.net>
上级
715c6b6d
变更
1
隐藏空白更改
内联
并排
Showing
1 changed file
with
34 addition
and
0 deletion
+34
-0
doc/README.fsync
doc/README.fsync
+34
-0
未找到文件。
doc/README.fsync
0 → 100644
浏览文件 @
5995953a
Fsync() patch (backend -F option)
=================================
Normally, the Postgres'95 backend makes sure that updates are actually
committed to disk by calling the standard function fsync() in
several places. Fsync() should guarantee that every modification to
a certain file is actually written to disk and will not hang around
in write caches anymore. This increases the chance that a database
will still be usable after a system crash by a large amount.
However, this operation severely slows down Postgres'95, because at all
those points it has to wait for the OS to flush the buffers. Especially
in one-shot operations, like creating a new database or loading lots
of data, you'll have a clear restart point if something goes wrong. That's
where the -F option kicks in: it simply disables the calls to fsync().
Without fsync(), the OS is allowed to do its best in buffering, sorting
and delaying writes, so this can be a _very_ big perfomance increase. However,
if the system crashes, large parts of the latest transactions will still hang
around in memory without having been committed to disk - lossage of data
is therefore almost certain to occur.
So it's a tradeoff between data integrity and speed. When initializing a
database, I'd use it - if the machine crashes, you simply remove the files
created and redo the operation. The same goes for bulk-loading data: on
a crash, you remove the database and restore the backup you made before
starting the bulk-load (you always make backups before bulk-loading,
don't you?).
Whether you want to use it in production, is up to you. If you trust your
operating system, your utility company, and your hardware, you might enable
it; however, keep in mind that you're running in an unsecure mode and that
performance gains will very much depend on access patterns (because it won't
help on reading data). I'd recommend against it.
编辑
预览
Markdown
is supported
0%
请重试
或
添加新附件
.
添加附件
取消
You are about to add
0
people
to the discussion. Proceed with caution.
先完成此消息的编辑!
取消
想要评论请
注册
或
登录