用sys.dm_exec_query_stats 动态管理查看查询最耗 IO 资源的 SQL 语法

经常朋友问某时间段系统响应慢，卡住。建议先查询哪些动作是导致性能下降原因。
/**SQL05**/
select --top 5
(total_logical_reads/execution_count) as [平均逻辑读取次数],
(total_logical_writes/execution_count) as [平均逻辑写入次数],
(total_physical_reads/execution_count) as [平均对象读取次数],
Execution_count 运行次数,
substring(qt.text,r.statement_start_offset/2+1,
(case when r.statement_end_offset = -1
then datalength(qt.text)
else r.statement_end_offset end - r.statement_start_offset)/2+1) [运行语法],getdate() [查询时间]
from sys.dm_exec_query_stats as r
cross apply sys.dm_exec_sql_text(r.sql_handle) as qt
order by
(total_logical_reads + total_logical_writes) Desc