原文地址：
http://technet.microsoft.com/zh-cn/library/bb838723.aspx
摘录部分精彩SQL如下：
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http://technet.microsoft.com/zh-cn/library/bb838723.aspx
Microsoft SQL Server 2005 提供了一些工具来监控数据库。方法之一是动态管理视图。动态管理视图 (DMV) 和动态管理函数 (DMF) 返回的服务器状态信息可用于监控服务器实例的运行状况、诊断问题和优化性能。
常规服务器动态管理对象包括：
-
dm_db_*：数据库和数据库对象
-
dm_exec_*：执行用户代码和关联的连接
-
dm_os_*：内存、锁定和时间安排
-
dm_tran_*：事务和隔离
-
dm_io_*：网络和磁盘的输入/输出
此部分介绍为监控 SQL Server 运行状况而针对这些动态管理视图和函数运行的一些常用查询。
摘录部分精彩SQL如下：
下面的查询显示 CPU 平均占用率最高的前 50 个 SQL 语句。
代码
SELECT
TOP
50
total_worker_time / execution_count AS [ Avg CPU Time ] ,
( SELECT SUBSTRING ( text ,statement_start_offset / 2 ,( CASE WHEN statement_end_offset = - 1 then LEN ( CONVERT ( nvarchar ( max ), text )) * 2 ELSE statement_end_offset end - statement_start_offset) / 2 ) FROM sys.dm_exec_sql_text(sql_handle)) AS query_text, *
FROM sys.dm_exec_query_stats
ORDER BY [ Avg CPU Time ] DESC
total_worker_time / execution_count AS [ Avg CPU Time ] ,
( SELECT SUBSTRING ( text ,statement_start_offset / 2 ,( CASE WHEN statement_end_offset = - 1 then LEN ( CONVERT ( nvarchar ( max ), text )) * 2 ELSE statement_end_offset end - statement_start_offset) / 2 ) FROM sys.dm_exec_sql_text(sql_handle)) AS query_text, *
FROM sys.dm_exec_query_stats
ORDER BY [ Avg CPU Time ] DESC
下面的查询显示一些可能占用大量 CPU 使用率的运算符（例如 ‘%Hash Match%’、‘%Sort%’）以找出可疑对象。
代码
select
*
from
sys.dm_exec_cached_plans
cross apply sys.dm_exec_query_plan(plan_handle)
where
cast (query_plan as nvarchar ( max )) like ' %Sort% '
or cast (query_plan as nvarchar ( max )) like ' %Hash Match% '
from
sys.dm_exec_cached_plans
cross apply sys.dm_exec_query_plan(plan_handle)
where
cast (query_plan as nvarchar ( max )) like ' %Sort% '
or cast (query_plan as nvarchar ( max )) like ' %Hash Match% '
运行下面的 DMV 查询以查看 CPU、计划程序内存和缓冲池信息。
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select
cpu_count,
hyperthread_ratio,
scheduler_count,
physical_memory_in_bytes / 1024 / 1024 as physical_memory_mb,
virtual_memory_in_bytes / 1024 / 1024 as virtual_memory_mb,
bpool_committed * 8 / 1024 as bpool_committed_mb,
bpool_commit_target * 8 / 1024 as bpool_target_mb,
bpool_visible * 8 / 1024 as bpool_visible_mb
from sys.dm_os_sys_info
cpu_count,
hyperthread_ratio,
scheduler_count,
physical_memory_in_bytes / 1024 / 1024 as physical_memory_mb,
virtual_memory_in_bytes / 1024 / 1024 as virtual_memory_mb,
bpool_committed * 8 / 1024 as bpool_committed_mb,
bpool_commit_target * 8 / 1024 as bpool_target_mb,
bpool_visible * 8 / 1024 as bpool_visible_mb
from sys.dm_os_sys_info
下面的示例查询显示已重新编译的前 25 个存储过程。 plan_generation_num 指示该查询已重新编译的次数。
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select
top
25
sql_text. text ,
sql_handle,
plan_generation_num,
execution_count,
dbid,
objectid
from sys.dm_exec_query_stats a
cross apply sys.dm_exec_sql_text(sql_handle) as sql_text
where plan_generation_num > 1
order by plan_generation_num desc
sql_text. text ,
sql_handle,
plan_generation_num,
execution_count,
dbid,
objectid
from sys.dm_exec_query_stats a
cross apply sys.dm_exec_sql_text(sql_handle) as sql_text
where plan_generation_num > 1
order by plan_generation_num desc
下面的 DMV 查询可用于查找哪些批处理/请求生成的 I/O 最多。如下所示的 DMV 查询可用于查找可生成最多 I/O 的前五个请求。调整这些查询将提高系统性能
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select
top
5
(total_logical_reads / execution_count) as avg_logical_reads,
(total_logical_writes / execution_count) as avg_logical_writes,
(total_physical_reads / execution_count) as avg_phys_reads,
Execution_count,
statement_start_offset as stmt_start_offset,
sql_handle,
plan_handle
from sys.dm_exec_query_stats
order by (total_logical_reads + total_logical_writes) Desc
(total_logical_reads / execution_count) as avg_logical_reads,
(total_logical_writes / execution_count) as avg_logical_writes,
(total_physical_reads / execution_count) as avg_phys_reads,
Execution_count,
statement_start_offset as stmt_start_offset,
sql_handle,
plan_handle
from sys.dm_exec_query_stats
order by (total_logical_reads + total_logical_writes) Desc
