SELECT TOP 50 SUM(qs.total_worker_time) AS total_cpu_time, SUM(qs.execution_count) AS total_execution_count,COUNT(*) AS  number_of_statements,
qs.sql_handle FROM sys.dm_exec_query_stats AS qsGROUP BY qs.sql_handleORDER BY SUM(qs.total_worker_time) DESC

SELECT
total_cpu_time,
total_execution_count,
number_of_statements,
s2.text--(SELECT SUBSTRING(s2.text, statement_start_offset / 2, ((CASE WHEN statement_end_offset = -1 THEN (LEN(CONVERT(NVARCHAR(MAX), s2.text)) * 2) ELSE statement_end_offset END) - statement_start_offset) / 2) ) AS query_textFROM
(SELECT TOP 50 SUM(qs.total_worker_time) AS total_cpu_time, SUM(qs.execution_count) AS total_execution_count,COUNT(*) AS  number_of_statements,
qs.sql_handle --,            --MIN(statement_start_offset) AS statement_start_offset,             --MAX(statement_end_offset) AS statement_end_offset      FROM
sys.dm_exec_query_stats AS qsGROUP BY qs.sql_handleORDER BY SUM(qs.total_worker_time) DESC) AS statsCROSS APPLY sys.dm_exec_sql_text(stats.sql_handle) AS s2

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

select * from sys.dm_exec_query_optimizer_infowhere
counter = 'optimizations'or counter = 'elapsed time'

select top 25
sql_text.text,
sql_handle,
plan_generation_num,
execution_count,
dbid,
objectid from sys.dm_exec_query_stats across apply sys.dm_exec_sql_text(sql_handle) as sql_textwhere plan_generation_num > 1order by plan_generation_num desc

SELECT
highest_cpu_queries.plan_handle,
highest_cpu_queries.total_worker_time,
q.dbid,
q.objectid,
q.number,
q.encrypted,
q.[text]from
(select top 50
qs.plan_handle,
qs.total_worker_timefrom
sys.dm_exec_query_stats qsorder by qs.total_worker_time desc) as highest_cpu_queriescross apply sys.dm_exec_sql_text(plan_handle) as qorder by highest_cpu_queries.total_worker_time desc

select *from
sys.dm_exec_cached_planscross 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%'

select * from sys.dm_exec_query_optimizer_infowhere
counter = 'optimizations'or counter = 'elapsed time'

select top 25
sql_text.text,
sql_handle,
plan_generation_num,
execution_count,
dbid,
objectid from sys.dm_exec_query_stats across apply sys.dm_exec_sql_text(sql_handle) as sql_textwhere plan_generation_num > 1order by plan_generation_num desc

开始内存压力检测和调查之前，请确保已启用 SQL Server 中的高级选项。请先对 master 数据库运行以下查询以启用此选项。

sp_configure 'show advanced options'go
sp_configure 'show advanced options', 1goreconfigurego

首先运行以下查询以检查内存相关配置选项。

sp_configure 'awe_enabled'go
sp_configure 'min server memory'go
sp_configure 'max server memory'go
sp_configure 'min memory per query'go
sp_configure 'query wait'go

运行下面的 DMV 查询以查看 CPU、计划程序内存和缓冲池信息。

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_mbfrom sys.dm_os_sys_info

I/O 瓶颈

检查闩锁等待统计信息以确定 I/O 瓶颈。运行下面的 DMV 查询以查找 I/O 闩锁等待统计信息。

select wait_type, waiting_tasks_count, wait_time_ms, signal_wait_time_ms, wait_time_ms / waiting_tasks_countfrom sys.dm_os_wait_stats  where wait_type like 'PAGEIOLATCH%'  and waiting_tasks_count > 0order by wait_type

如果 waiting_task_counts 和 wait_time_ms 与正常情况相比有显著变化，则可以确定存在 I/O 问题。获取 SQL Server 平稳运行时性能计数器和主要 DMV 查询输出的基线非常重要。

这些 wait_types 可以指示您的 I/O 子系统是否遇到瓶颈。

使用以下 DMV 查询来查找当前挂起的 I/O 请求。请定期执行此查询以检查 I/O 子系统的运行状况，并隔离 I/O 瓶颈中涉及的物理磁盘。

select
database_id, file_id,
io_stall,
io_pending_ms_ticks,
scheduler_address from  sys.dm_io_virtual_file_stats(NULL, NULL)t1,
sys.dm_io_pending_io_requests as t2where t1.file_handle = t2.io_handle

在正常情况下，该查询通常不返回任何内容。如果此查询返回一些行，则需要进一步调查。

您还可以执行下面的 DMV 查询以查找 I/O 相关查询。

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_physical_reads,
Execution_count, statement_start_offset, p.query_plan, q.textfrom sys.dm_exec_query_statscross apply sys.dm_exec_query_plan(plan_handle) pcross apply sys.dm_exec_sql_text(plan_handle) as qorder by (total_logical_reads + total_logical_writes)/execution_count 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。

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_handlefrom sys.dm_exec_query_stats  order by  (total_logical_reads + total_logical_writes) Desc

阻塞

运行下面的查询可确定阻塞的会话。

select blocking_session_id, wait_duration_ms, session_id from
sys.dm_os_waiting_taskswhere blocking_session_id is not null

使用此调用可找出 blocking_session_id 所返回的 SQL。例如，如果 blocking_session_id 是 87，则运行此查询可获得相应的 SQL。

dbcc INPUTBUFFER(87)

下面的查询显示 SQL 等待分析和前 10 个等待的资源。

select top 10 *from sys.dm_os_wait_stats--where wait_type not in ('CLR_SEMAPHORE','LAZYWRITER_SLEEP','RESOURCE_QUEUE','SLEEP_TASK','SLEEP_SYSTEMTASK','WAITFOR')order by wait_time_ms desc

若要找出哪个 spid 正在阻塞另一个 spid，可在数据库中创建以下存储过程，然后执行该存储过程。此存储过程会报告此阻塞情况。键入 sp_who 可找出 @spid；@spid 是可选参数。

create proc dbo.sp_block (@spid bigint=NULL)asselect
t1.resource_type,'database'=db_name(resource_database_id),'blk object' = t1.resource_associated_entity_id,
t1.request_mode,
t1.request_session_id,
t2.blocking_session_id    from
sys.dm_tran_locks as t1,
sys.dm_os_waiting_tasks as t2where
t1.lock_owner_address = t2.resource_address and
t1.request_session_id = isnull(@spid,t1.request_session_id)

以下是使用此存储过程的示例。

exec sp_blockexec sp_block @spid = 7

本文转自王磊的博客博客园博客，原文链接：http://www.cnblogs.com/vipstone/archive/2011/10/10/2205010.html，如需转载请自行联系原作者