SQLSERVER数据库调优

--查看锁住的表
select   request_session_id   spid,OBJECT_NAME(resource_associated_entity_id) tableName  
from   sys.dm_tran_locks where resource_type=‘OBJECT‘

--哪个会话引起阻塞并且它们在运行什么 
SELECT  DTL.[request_session_id] AS [session_id] ,
        DB_NAME(DTL.[resource_database_id]) AS [Database] ,
        DTL.resource_type ,
        CASE WHEN DTL.resource_type IN ( ‘DATABASE‘, ‘FILE‘, ‘METADATA‘ )
             THEN DTL.resource_type
             WHEN DTL.resource_type = ‘OBJECT‘
             THEN OBJECT_NAME(DTL.resource_associated_entity_id,
                              DTL.[resource_database_id])
             WHEN DTL.resource_type IN ( ‘KEY‘, ‘PAGE‘, ‘RID‘ )
             THEN ( SELECT  OBJECT_NAME([object_id])
                    FROM    sys.partitions
                    WHERE   sys.partitions.hobt_id = DTL.resource_associated_entity_id
                  )
             ELSE ‘Unidentified‘
        END AS [Parent Object] ,
        DTL.request_mode AS [Lock Type] ,
        DTL.request_status AS [Request Status] ,
        DER.[blocking_session_id] ,
        DES.[login_name] ,
        CASE DTL.request_lifetime
          WHEN 0 THEN DEST_R.TEXT
          ELSE DEST_C.TEXT
        END AS [Statement]
FROM    sys.dm_tran_locks DTL
        LEFT JOIN sys.[dm_exec_requests] DER ON DTL.[request_session_id] = DER.[session_id]
        INNER JOIN sys.dm_exec_sessions DES ON DTL.request_session_id = DES.[session_id]
        INNER JOIN sys.dm_exec_connections DEC ON DTL.[request_session_id] = DEC.[most_recent_session_id]
        OUTER APPLY sys.dm_exec_sql_text(DEC.[most_recent_sql_handle]) AS DEST_C
        OUTER APPLY sys.dm_exec_sql_text(DER.sql_handle) AS DEST_R
WHERE   DTL.[resource_database_id] = DB_ID()
        AND DTL.[resource_type] NOT IN ( ‘DATABASE‘, ‘METADATA‘ )
ORDER BY DTL.[request_session_id];

--查看因为单条UPDATE语句锁住的用户表
SELECT  [resource_type] ,
        DB_NAME([resource_database_id]) AS [Database Name] ,
        CASE WHEN DTL.resource_type IN ( ‘DATABASE‘, ‘FILE‘, ‘METADATA‘ )
             THEN DTL.resource_type
             WHEN DTL.resource_type = ‘OBJECT‘
             THEN OBJECT_NAME(DTL.resource_associated_entity_id,
                              DTL.[resource_database_id])
             WHEN DTL.resource_type IN ( ‘KEY‘, ‘PAGE‘, ‘RID‘ )
             THEN ( SELECT  OBJECT_NAME([object_id])
                    FROM    sys.partitions
                    WHERE   sys.partitions.hobt_id = DTL.resource_associated_entity_id
                  )
             ELSE ‘Unidentified‘
        END AS requested_object_name ,
        [request_mode] ,
        [resource_description]
FROM    sys.dm_tran_locks DTL
WHERE   DTL.[resource_type] <> ‘DATABASE‘;

--单库中的锁定和阻塞
SELECT  DTL.[resource_type] AS [resource type] ,
        CASE WHEN DTL.[resource_type] IN ( ‘DATABASE‘, ‘FILE‘, ‘METADATA‘ )
             THEN DTL.[resource_type]
             WHEN DTL.[resource_type] = ‘OBJECT‘
             THEN OBJECT_NAME(DTL.resource_associated_entity_id)
             WHEN DTL.[resource_type] IN ( ‘KEY‘, ‘PAGE‘, ‘RID‘ )
             THEN ( SELECT  OBJECT_NAME([object_id])
                    FROM    sys.partitions
                    WHERE   sys.partitions.[hobt_id] = DTL.[resource_associated_entity_id]
                  )
             ELSE ‘Unidentified‘
        END AS [Parent Object] ,
        DTL.[request_mode] AS [Lock Type] ,
        DTL.[request_status] AS [Request Status] ,
        DOWT.[wait_duration_ms] AS [wait duration ms] ,
        DOWT.[wait_type] AS [wait type] ,
        DOWT.[session_id] AS [blocked session id] ,
        DES_blocked.[login_name] AS [blocked_user] ,
        SUBSTRING(dest_blocked.text, der.statement_start_offset / 2,
                  ( CASE WHEN der.statement_end_offset = -1
                         THEN DATALENGTH(dest_blocked.text)
                         ELSE der.statement_end_offset
                    END - der.statement_start_offset ) / 2) AS [blocked_command] ,
        DOWT.[blocking_session_id] AS [blocking session id] ,
        DES_blocking.[login_name] AS [blocking user] ,
        DEST_blocking.[text] AS [blocking command] ,
        DOWT.resource_description AS [blocking resource detail]
FROM    sys.dm_tran_locks DTL
        INNER JOIN sys.dm_os_waiting_tasks DOWT ON DTL.lock_owner_address = DOWT.resource_address
        INNER JOIN sys.[dm_exec_requests] DER ON DOWT.[session_id] = DER.[session_id]
        INNER JOIN sys.dm_exec_sessions DES_blocked ON DOWT.[session_id] = DES_Blocked.[session_id]
        INNER JOIN sys.dm_exec_sessions DES_blocking ON DOWT.[blocking_session_id] = DES_Blocking.[session_id]
        INNER JOIN sys.dm_exec_connections DEC ON DTL.[request_session_id] = DEC.[most_recent_session_id]
        CROSS APPLY sys.dm_exec_sql_text(DEC.[most_recent_sql_handle]) AS DEST_Blocking
        CROSS APPLY sys.dm_exec_sql_text(DER.sql_handle) AS DEST_Blocked
WHERE   DTL.[resource_database_id] = DB_ID()


--识别在行级的锁定和阻塞
SELECT  ‘[‘ + DB_NAME(ddios.[database_id]) + ‘].[‘ + su.[name] + ‘].[‘
        + o.[name] + ‘]‘ AS [statement] ,
        i.[name] AS ‘index_name‘ ,
        ddios.[partition_number] ,
        ddios.[row_lock_count] ,
        ddios.[row_lock_wait_count] ,
        CAST (100.0 * ddios.[row_lock_wait_count] / ( ddios.[row_lock_count] ) AS DECIMAL(5,
                                                              2)) AS [%_times_blocked] ,
        ddios.[row_lock_wait_in_ms] ,
        CAST (1.0 * ddios.[row_lock_wait_in_ms] / ddios.[row_lock_wait_count] AS DECIMAL(15,
                                                              2)) AS [avg_row_lock_wait_in_ms]
FROM    sys.dm_db_index_operational_stats(DB_ID(), NULL, NULL, NULL) ddios
        INNER JOIN sys.indexes i ON ddios.[object_id] = i.[object_id]
                                    AND i.[index_id] = ddios.[index_id]
        INNER JOIN sys.objects o ON ddios.[object_id] = o.[object_id]
        INNER JOIN sys.sysusers su ON o.[schema_id] = su.[UID]
WHERE   ddios.row_lock_wait_count > 0
        AND OBJECTPROPERTY(ddios.[object_id], ‘IsUserTable‘) = 1
        AND i.[index_id] > 0
ORDER BY ddios.[row_lock_wait_count] DESC ,
        su.[name] ,
        o.[name] ,
        i.[name]

--识别闩锁等待
SELECT  ‘[‘ + DB_NAME() + ‘].[‘ + OBJECT_SCHEMA_NAME(ddios.[object_id])
        + ‘].[‘ + OBJECT_NAME(ddios.[object_id]) + ‘]‘ AS [object_name] ,
        i.[name] AS index_name ,
        ddios.page_io_latch_wait_count ,
        ddios.page_io_latch_wait_in_ms ,
        ( ddios.page_io_latch_wait_in_ms / ddios.page_io_latch_wait_count ) AS avg_page_io_latch_wait_in_ms
FROM    sys.dm_db_index_operational_stats(DB_ID(), NULL, NULL, NULL) ddios
        INNER JOIN sys.indexes i ON ddios.[object_id] = i.[object_id]
                                    AND i.index_id = ddios.index_id
WHERE   ddios.page_io_latch_wait_count > 0
        AND OBJECTPROPERTY(i.object_id, ‘IsUserTable‘) = 1
ORDER BY ddios.page_io_latch_wait_count DESC ,
        avg_page_io_latch_wait_in_ms DESC

--识别锁升级
SELECT  OBJECT_NAME(ddios.[object_id], ddios.database_id) AS [object_name] ,
        i.name AS index_name ,
        ddios.index_id ,
        ddios.partition_number ,
        ddios.index_lock_promotion_attempt_count ,
        ddios.index_lock_promotion_count ,
        ( ddios.index_lock_promotion_attempt_count
          / ddios.index_lock_promotion_count ) AS percent_success
FROM    sys.dm_db_index_operational_stats(DB_ID(), NULL, NULL, NULL) ddios
        INNER JOIN sys.indexes i ON ddios.object_id = i.object_id
                                    AND ddios.index_id = i.index_id
WHERE   ddios.index_lock_promotion_count > 0
ORDER BY index_lock_promotion_count DESC;

--与锁争用有关的索引
SELECT  OBJECT_NAME(ddios.object_id, ddios.database_id) AS object_name ,
        i.name AS index_name ,
        ddios.index_id ,
        ddios.partition_number ,
        ddios.page_lock_wait_count ,
        ddios.page_lock_wait_in_ms ,
        CASE WHEN DDMID.database_id IS NULL THEN ‘N‘
             ELSE ‘Y‘
        END AS missing_index_identified
FROM    sys.dm_db_index_operational_stats(DB_ID(), NULL, NULL, NULL) ddios
        INNER JOIN sys.indexes i ON ddios.object_id = i.object_id
                                    AND ddios.index_id = i.index_id
        LEFT OUTER JOIN ( SELECT DISTINCT
                                    database_id ,
                                    object_id
                          FROM      sys.dm_db_missing_index_details
                        ) AS DDMID ON DDMID.database_id = ddios.database_id
                                      AND DDMID.object_id = ddios.object_id
WHERE   ddios.page_lock_wait_in_ms > 0
ORDER BY ddios.page_lock_wait_count DESC;

-- 未被使用的索引
SELECT  OBJECT_NAME(i.[object_id]) AS [Table Name] ,
        i.name
FROM    sys.indexes AS i
        INNER JOIN sys.objects AS o ON i.[object_id] = o.[object_id]
WHERE   i.index_id NOT IN ( SELECT  ddius.index_id
                            FROM    sys.dm_db_index_usage_stats AS ddius
                            WHERE   ddius.[object_id] = i.[object_id]
                                    AND i.index_id = ddius.index_id
                                    AND database_id = DB_ID() )
        AND o.[type] = ‘U‘
ORDER BY OBJECT_NAME(i.[object_id]) ASC;

--需要维护但是未被用过的索引
SELECT  ‘[‘ + DB_NAME() + ‘].[‘ + su.[name] + ‘].[‘ + o.[name] + ‘]‘ AS [statement] ,
        i.[name] AS [index_name] ,
        ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] AS [user_reads] ,
        ddius.[user_updates] AS [user_writes] ,
        SUM(SP.rows) AS [total_rows]
FROM    sys.dm_db_index_usage_stats ddius
        INNER JOIN sys.indexes i ON ddius.[object_id] = i.[object_id]
                                    AND i.[index_id] = ddius.[index_id]
        INNER JOIN sys.partitions SP ON ddius.[object_id] = SP.[object_id]
                                        AND SP.[index_id] = ddius.[index_id]
        INNER JOIN sys.objects o ON ddius.[object_id] = o.[object_id]
        INNER JOIN sys.sysusers su ON o.[schema_id] = su.[UID]
WHERE   ddius.[database_id] = DB_ID() -- current database only
        AND OBJECTPROPERTY(ddius.[object_id], ‘IsUserTable‘) = 1
        AND ddius.[index_id] > 0
GROUP BY su.[name] ,
        o.[name] ,
        i.[name] ,
        ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] ,
        ddius.[user_updates]
HAVING  ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] = 0
ORDER BY ddius.[user_updates] DESC ,
        su.[name] ,
        o.[name] ,
        i.[name]

-- 可能不高效的非聚集索引 (writes > reads)
SELECT  OBJECT_NAME(ddius.[object_id]) AS [Table Name] ,
        i.name AS [Index Name] ,
        i.index_id ,
        user_updates AS [Total Writes] ,
        user_seeks + user_scans + user_lookups AS [Total Reads] ,
        user_updates - ( user_seeks + user_scans + user_lookups ) AS [Difference]
FROM    sys.dm_db_index_usage_stats AS ddius WITH ( NOLOCK )
        INNER JOIN sys.indexes AS i WITH ( NOLOCK ) ON ddius.[object_id] = i.[object_id]
                                                       AND i.index_id = ddius.index_id
WHERE   OBJECTPROPERTY(ddius.[object_id], ‘IsUserTable‘) = 1
        AND ddius.database_id = DB_ID()
        AND user_updates > ( user_seeks + user_scans + user_lookups )
        AND i.index_id > 1
ORDER BY [Difference] DESC ,
        [Total Writes] DESC ,
        [Total Reads] ASC;

--没有用于用户查询的索引
SELECT  ‘[‘ + DB_NAME() + ‘].[‘ + su.[name] + ‘].[‘ + o.[name] + ‘]‘ AS [statement] ,
        i.[name] AS [index_name] ,
        ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] AS [user_reads] ,
        ddius.[user_updates] AS [user_writes] ,
        ddios.[leaf_insert_count] ,
        ddios.[leaf_delete_count] ,
        ddios.[leaf_update_count] ,
        ddios.[nonleaf_insert_count] ,
        ddios.[nonleaf_delete_count] ,
        ddios.[nonleaf_update_count]
FROM    sys.dm_db_index_usage_stats ddius
        INNER JOIN sys.indexes i ON ddius.[object_id] = i.[object_id]
                                    AND i.[index_id] = ddius.[index_id]
        INNER JOIN sys.partitions SP ON ddius.[object_id] = SP.[object_id]
                                        AND SP.[index_id] = ddius.[index_id]
        INNER JOIN sys.objects o ON ddius.[object_id] = o.[object_id]
        INNER JOIN sys.sysusers su ON o.[schema_id] = su.[UID]
        INNER JOIN sys.[dm_db_index_operational_stats](DB_ID(), NULL, NULL,
                                                       NULL) AS ddios ON ddius.[index_id] = ddios.[index_id]
                                                              AND ddius.[object_id] = ddios.[object_id]
                                                              AND SP.[partition_number] = ddios.[partition_number]
                                                              AND ddius.[database_id] = ddios.[database_id]
WHERE   OBJECTPROPERTY(ddius.[object_id], ‘IsUserTable‘) = 1
        AND ddius.[index_id] > 0
        AND ddius.[user_seeks] + ddius.[user_scans] + ddius.[user_lookups] = 0
ORDER BY ddius.[user_updates] DESC ,
        su.[name] ,
        o.[name] ,
        i.[name]

--查找丢失索引
SELECT  user_seeks * avg_total_user_cost * ( avg_user_impact * 0.01 ) AS [index_advantage] ,
        dbmigs.last_user_seek ,
        dbmid.[statement] AS [Database.Schema.Table] ,
        dbmid.equality_columns ,
        dbmid.inequality_columns ,
        dbmid.included_columns ,
        dbmigs.unique_compiles ,
        dbmigs.user_seeks ,
        dbmigs.avg_total_user_cost ,
        dbmigs.avg_user_impact
FROM    sys.dm_db_missing_index_group_stats AS dbmigs WITH ( NOLOCK )
        INNER JOIN sys.dm_db_missing_index_groups AS dbmig WITH ( NOLOCK ) ON dbmigs.group_handle = dbmig.index_group_handle
        INNER JOIN sys.dm_db_missing_index_details AS dbmid WITH ( NOLOCK ) ON dbmig.index_handle = dbmid.index_handle
WHERE   dbmid.[database_id] = DB_ID()
ORDER BY index_advantage DESC;

--索引上的碎片超过15%并且索引体积较大（超过500页）的索引。
SELECT  ‘[‘ + DB_NAME() + ‘].[‘ + OBJECT_SCHEMA_NAME(ddips.[object_id],
                                                     DB_ID()) + ‘].[‘
        + OBJECT_NAME(ddips.[object_id], DB_ID()) + ‘]‘ AS [statement] ,
        i.[name] AS [index_name] ,
        ddips.[index_type_desc] ,
        ddips.[partition_number] ,
        ddips.[alloc_unit_type_desc] ,
        ddips.[index_depth] ,
        ddips.[index_level] ,
        CAST(ddips.[avg_fragmentation_in_percent] AS SMALLINT) AS [avg_frag_%] ,
        CAST(ddips.[avg_fragment_size_in_pages] AS SMALLINT) AS [avg_frag_size_in_pages] ,
        ddips.[fragment_count] ,
        ddips.[page_count]
FROM    sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, ‘limited‘) ddips
        INNER JOIN sys.[indexes] i ON ddips.[object_id] = i.[object_id]
                                      AND ddips.[index_id] = i.[index_id]
WHERE   ddips.[avg_fragmentation_in_percent] > 15
        AND ddips.[page_count] > 500
ORDER BY ddips.[avg_fragmentation_in_percent] ,
        OBJECT_NAME(ddips.[object_id], DB_ID()) ,
        i.[name]

--缺失索引
SELECT migs.group_handle, mid.* 
FROM sys.dm_db_missing_index_group_stats AS migs 
INNER JOIN sys.dm_db_missing_index_groups AS mig 
ON (migs.group_handle = mig.index_group_handle) 
INNER JOIN sys.dm_db_missing_index_details AS mid 
ON (mig.index_handle = mid.index_handle) 
WHERE migs.group_handle = 2

--无用索引
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED 
SELECT 
DB_NAME() AS DatbaseName 
, SCHEMA_NAME(O.Schema_ID) AS SchemaName 
, OBJECT_NAME(I.object_id) AS TableName 
, I.name AS IndexName 
INTO #TempNeverUsedIndexes 
FROM sys.indexes I INNER JOIN sys.objects O ON I.object_id = O.object_id 
WHERE 1=2 
EXEC sp_MSForEachDB ‘USE [?]; INSERT INTO #TempNeverUsedIndexes 
SELECT 
DB_NAME() AS DatbaseName 
, SCHEMA_NAME(O.Schema_ID) AS SchemaName 
, OBJECT_NAME(I.object_id) AS TableName 
, I.NAME AS IndexName 
FROM sys.indexes I INNER JOIN sys.objects O ON I.object_id = O.object_id 
LEFT OUTER JOIN sys.dm_db_index_usage_stats S ON S.object_id = I.object_id 
AND I.index_id = S.index_id 
AND DATABASE_ID = DB_ID() 
WHERE OBJECTPROPERTY(O.object_id,‘‘IsMsShipped‘‘) = 0 
AND I.name IS NOT NULL 
AND S.object_id IS NULL‘ 
SELECT * FROM #TempNeverUsedIndexes 
ORDER BY DatbaseName, SchemaName, TableName, IndexName 
DROP TABLE #TempNeverUsedIndexes

--经常被大量更新，但是却基本不适用的索引项-
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED 
SELECT 
DB_NAME() AS DatabaseName 
, SCHEMA_NAME(o.Schema_ID) AS SchemaName 
, OBJECT_NAME(s.[object_id]) AS TableName 
, i.name AS IndexName 
, s.user_updates 
, s.system_seeks + s.system_scans + s.system_lookups 
AS [System usage] 
INTO #TempUnusedIndexes 
FROM sys.dm_db_index_usage_stats s 
INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id] 
AND s.index_id = i.index_id 
INNER JOIN sys.objects o ON i.object_id = O.object_id 
WHERE 1=2 
EXEC sp_MSForEachDB ‘USE [?]; INSERT INTO #TempUnusedIndexes 
SELECT TOP 20 
DB_NAME() AS DatabaseName 
, SCHEMA_NAME(o.Schema_ID) AS SchemaName 
, OBJECT_NAME(s.[object_id]) AS TableName 
, i.name AS IndexName 
, s.user_updates 
, s.system_seeks + s.system_scans + s.system_lookups 
AS [System usage] 
FROM sys.dm_db_index_usage_stats s 
INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id] 
AND s.index_id = i.index_id 
INNER JOIN sys.objects o ON i.object_id = O.object_id 
WHERE s.database_id = DB_ID() 
AND OBJECTPROPERTY(s.[object_id], ‘‘IsMsShipped‘‘) = 0 
AND s.user_seeks = 0 
AND s.user_scans = 0 
AND s.user_lookups = 0 
AND i.name IS NOT NULL 
ORDER BY s.user_updates DESC‘ 
SELECT TOP 20 * FROM #TempUnusedIndexes ORDER BY [user_updates] DESC 
DROP TABLE #TempUnusedIndexes

--查询当前数据库的配置信息
Select configuration_id ConfigurationId,
name Name,
description Description,
Cast(value as int) value,
Cast(minimum as int) Minimum,
Cast(maximum as int) Maximum,
Cast(value_in_use as int) ValueInUse,
is_dynamic IsDynamic,
is_advanced IsAdvanced
From sys.configurations
Order By is_advanced, name

--检查SQL SERVER 当前已创建的线程数
select count(*) from sys.dm_os_workers

--查询当前连接到数据库的用户信息
Select s.login_name LoginName,
s.host_name HostName,
s.transaction_isolation_level TransactionIsolationLevel,
Max(c.connect_time) LastConnectTime,
Count(*) ConnectionCount,
Sum(Cast(c.num_reads as BigInt)) TotalReads,
Sum(Cast(c.num_writes as BigInt)) TotalWrites
From sys.dm_exec_connections c
Join sys.dm_exec_sessions s
On c.most_recent_session_id = s.session_id
Group By s.login_name, s.host_name, s.transaction_isolation_level

--查询CPU和内存利用率
Select DateAdd(s, (timestamp - (osi.cpu_ticks / Convert(Float, (osi.cpu_ticks / osi.ms_ticks)))) / 1000, GETDATE()) AS EventTime,
Record.value(‘(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]‘, ‘int‘) as SystemIdle,
Record.value(‘(./Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]‘, ‘int‘) as ProcessUtilization,
Record.value(‘(./Record/SchedulerMonitorEvent/SystemHealth/MemoryUtilization)[1]‘, ‘int‘) as MemoryUtilization
From (Select timestamp,
convert(xml, record) As Record
From sys.dm_os_ring_buffers
Where ring_buffer_type = N‘RING_BUFFER_SCHEDULER_MONITOR‘
And record Like ‘%<SystemHealth>%‘) x
Cross Join sys.dm_os_sys_info osi
Order By timestamp

--查看每个数据库缓存大小
SELECT  COUNT(*) * 8 / 1024 AS ‘Cached Size (MB)‘ ,
        CASE database_id
          WHEN 32767 THEN ‘ResourceDb‘
          ELSE DB_NAME(database_id)
        END AS ‘Database‘
FROM    sys.dm_os_buffer_descriptors
GROUP BY DB_NAME(database_id) ,
        database_id
ORDER BY ‘Cached Size (MB)‘ DESC


--SQL SERVER  统计IO活动信息
SET STATISTICS IO ON
select top 10* from Table
SET STATISTICS IO OFF

--SQL SERVER 清除缓存SQL语句
CHECKPOINT;
GO
DBCC  FREEPROCCACHE      ---清空执行计划缓存
DBCC DROPCLEANBUFFERS;   --清空数据缓存
GO

--查看当前进程的信息
DBCC INPUTBUFFER(51)

--查看当前数据是否启用了快照隔离
DBCC USEROPTIONS;

--查看摸个数据库数据表中的数据页类型
--In_Row_Data: 分别为存储行内数据的
    --LOB_Data: 存储Lob对象,Lob对象用于存储存在数据库的二进制文件
              --当这个类型的列出现时,原有的列会存储一个24字节的指针，而将具体的二进制数据存在LOB页中
    --Row_Overflow_data:存储溢出数据的,使用Varchar,nvarchar等数据类型时，当行的大小不超过8060字节时，全部存在行内In-row data
                    --当varchar中存储的数据过多使得整行超过8060字节时，会将额外的部分存于Row-overflow data页中，
                    --如果update这列使得行大小减少到小于8060字节，则这行又会全部回到in-row data页
                    --text,ntext和image类型来说，每一列只要不为null,即使占用很小的数据，也需要额外分配一个LOB页
DBCC IND ( Lawyer, [dbo.tb_Contract], -1)

--查询CPU最高的10条SQL
SELECT TOP 10 TEXT AS ‘SQL Statement‘
    ,last_execution_time AS ‘Last Execution Time‘
    ,(total_logical_reads + total_physical_reads + total_logical_writes) / execution_count AS [Average IO]
    ,(total_worker_time / execution_count) / 1000000.0 AS [Average CPU Time (sec)]
    ,(total_elapsed_time / execution_count) / 1000000.0 AS [Average Elapsed Time (sec)]
    ,execution_count AS "Execution Count",qs.total_physical_reads,qs.total_logical_writes
    ,qp.query_plan AS "Query Plan"
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.plan_handle) st
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
ORDER BY total_elapsed_time / execution_count DESC


--找出执行频繁的语句的SQL语句
with aa as (
SELECT  
--执行次数 
QS.execution_count, 
--查询语句 
SUBSTRING(ST.text,(QS.statement_start_offset/2)+1, 
((CASE QS.statement_end_offset WHEN -1 THEN DATALENGTH(st.text) 
ELSE QS.statement_end_offset END - QS.statement_start_offset)/2) + 1 
) AS statement_text, 
--执行文本 
ST.text, 
--执行计划 
qs.last_elapsed_time,
qs.min_elapsed_time,
qs.max_elapsed_time,
QS.total_worker_time, 
QS.last_worker_time, 
QS.max_worker_time, 
QS.min_worker_time 
FROM 
sys.dm_exec_query_stats QS 
--关键字 
CROSS APPLY 
sys.dm_exec_sql_text(QS.sql_handle) ST 
WHERE 
QS.last_execution_time > ‘2016-02-14 00:00:00‘ and  execution_count > 500

-- AND ST.text LIKE ‘%%‘ 
--ORDER BY 
--QS.execution_count DESC

)
select text,max(execution_count) execution_count --,last_elapsed_time,min_elapsed_time,max_elapsed_time 
from aa
where [text] not  like ‘%sp_MSupd_%‘ and  [text] not like ‘%sp_MSins_%‘ and  [text] not like ‘%sp_MSdel_%‘ 
group by text
order by 2  desc


-- 查找逻辑读取最高的查询(存储过程)
SELECT TOP ( 25 )
        P.name AS [SP Name] ,
        Deps.total_logical_reads AS [TotalLogicalReads] ,
        deps.total_logical_reads / deps.execution_count AS [AvgLogicalReads] ,
        deps.execution_count ,
        ISNULL(deps.execution_count / DATEDIFF(Second, deps.cached_time,
                                               GETDATE()), 0) AS [Calls/Second] ,
        deps.total_elapsed_time ,
        deps.total_elapsed_time / deps.execution_count AS [avg_elapsed_time] ,
        deps.cached_time
FROM    sys.procedures AS p
        INNER JOIN sys.dm_exec_procedure_stats AS deps ON p.[Object_id] = deps.[Object_id]
WHERE   deps.Database_id = DB_ID()
ORDER BY deps.total_logical_reads DESC;

SELECT  creation_time  N‘语句编译时间‘
        ,last_execution_time  N‘上次执行时间‘
        ,total_physical_reads N‘物理读取总次数‘
        ,total_logical_reads/execution_count N‘每次逻辑读次数‘
        ,total_logical_reads  N‘逻辑读取总次数‘
        ,total_logical_writes N‘逻辑写入总次数‘
        , execution_count  N‘执行次数‘
        , total_worker_time/1000 N‘所用的CPU总时间ms‘
        , total_elapsed_time/1000  N‘总花费时间ms‘
        , (total_elapsed_time / execution_count)/1000  N‘平均时间ms‘
        ,SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,
         ((CASE statement_end_offset 
          WHEN -1 THEN DATALENGTH(st.text)
          ELSE qs.statement_end_offset END 
            - qs.statement_start_offset)/2) + 1) N‘执行语句‘
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st
where SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,
         ((CASE statement_end_offset 
          WHEN -1 THEN DATALENGTH(st.text)
          ELSE qs.statement_end_offset END 
            - qs.statement_start_offset)/2) + 1) not like ‘%fetch%‘
ORDER BY  total_elapsed_time / execution_count DESC;