对《SQL Server中tempdb的management》的一些更正和补充
对《SQL Server中tempdb的management》的一些更正和补充 前几天看了这篇文章：SQL Server中tempdb的management 发现里面有些内容不是很准确 文章中说到： TempDB和其他用户数据库一样以Model数据库为模板创建，并且可以创建和查询表格。 与其他用户数据库不
对《SQL Server中tempdb的management》的一些更正和补充
前几天看了这篇文章：SQL Server中tempdb的management
发现里面有些内容不是很准确
文章中说到：
TempDB和其他用户数据库一样以Model数据库为模板创建，并且可以创建和查询表格。
与其他用户数据库不同的是，TempDB在每次SQL Server启动的时候都会被重新创建。
我打开SQLSERVER2005，对比了一下model数据库和tempdb数据库，发现还是有一些不同
初始大小和自动增长、跨数据库所有权链接已启用这里不讨论
跨数据库所有权链接：
页面验证里面，，model数据库页面验证用的是checksum，但是tempdb没有页面验证
tempdb不使用页面验证究竟好还是不好？？？
讨论这个问题之前，这里要先了解一下checksum的功能
以下摘抄自：
页面 CHECKSUM:
在数据库页面从被写入磁盘到被SQL Server读取的这段时间内，有可能由于外界原因发生损坏。
比如I/O设备的损坏，驱动的损坏或者由于电源不稳没有写完整。Checksum机制使SQL Server可以检测到这些损坏。
需要注意的是，Checksum机制只能使我们确定是不是I/O子系统引起页面损坏，但是不能自动修复它们。
作为管理员，我们可以利用这些信息来辨识出并更换损坏的I/O设备，
也可以利用重建索引或者修复损坏文件等方法修复已发生的页面损坏。
计算checksum的算法是复杂的，因为会涉及到多个页面的读写，增加CPU的负荷，可能会影响系统的吞吐量
系统吞吐量、CPU负荷这个本人觉得可以忽略不计，因为用户数据库默认都是开启了checksum页面验证的
所以本人觉得还是有必要开启checksum页面验证
页面checksum的条件：在数据库页面从被写入磁盘到被SQL Server读取的这段时间内，数据页一定要写入到磁盘，
如果数据页面没有写入到磁盘，那么开启checksum也就没有什么用处
在tempdb里，无论是数据页还是索引页还是版本存储区里的页面都有可能写入磁盘
版本存储区的资料：
版本存储区也和数据页面索引页面一样由8k大小的页组成。这些页存在缓冲池中，可以在TempDB面临内存压力时被写入磁盘
如果是这样，那么SQLSERVER应该要开启tempdb数据库的checksum页面验证才对啊
很可惜，本人暂时还没有在网上找到相关解释
不过通过下面实验，本人猜测了一些SQLSERVER团队的意图
这些实验在文章SQL Server中tempdb的management里已经给出了，本人只是做一些补充
实验
以下实验的实验环境：Windows7，SQLSERVER2005个人开发者版
全局临时表
通过创建##t_tempdblog全局临时表，插入数据，修改数据，删除数据，建立聚集索引，删除聚集索引，建立非聚集索引，删除非聚集索引
查看事务日志文件里有没有相关的操作记录
测试脚本
插入记录
1 use tempdb ##t_tempdblog ##t_tempdblog (c1 int, c2 char(1000)) () ##t_tempdblog ), 1000)) operation,context, , , fn_dblog(null, null)
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