sql server 性能优化方法
--查看是否有死锁
dECLARE @tab TABLE(NAME varchar(100),value varchar(200));
INSERT INTO @tab EXEC('DBCC OPENTRAN WITH TABLERESULTS');
SELECT name,CAST(value AS DATETIME) startDate,getdate() currentDate
,DATEDIFF(s,CAST(value AS DATETIME),getdate()) diffsecond FROM @tab WHERE name in
('OLDACT_STARTTIME')
SELECT spid,
blocked,
DB_NAME(sp.dbid) AS DBName,
program_name,
waitresource,
lastwaittype,
sp.loginame,
sp.hostname,
a.[Text] AS [TextData],
SUBSTRING(A.text, sp.stmt_start / 2,
(CASE WHEN sp.stmt_end = -1 THEN DATALENGTH(A.text) ELSE sp.stmt_end
END - sp.stmt_start) / 2) AS [current_cmd]
FROM sys.sysprocesses AS sp OUTER APPLY sys.dm_exec_sql_text (sp.sql_handle) AS A
WHERE spid =(SELECT CASE WHEN ISNUMERIC(value)=0 THEN -1 ELSE value end FROM @tab WHERE name in
('OLDACT_SPID') )
--查看当前正在执行的sql语句
SELECT [Spid] = session_id , ecid ,
[Database] = DB_NAME(sp.dbid) ,[User] = nt_username ,
[Status] = er.status , [Wait] = wait_type ,
[Individual Query] = SUBSTRING(qt.text,
er.statement_start_offset / 2,
( CASE WHEN er.statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), qt.text))
* 2
ELSE er.statement_end_offset
END - er.statement_start_offset )
/ 2) ,
[Parent Query] = qt.text , Program = program_name ,hostname , nt_domain , start_time
FROM sys.dm_exec_requests er
INNER JOIN sys.sysprocesses sp ON er.session_id = sp.spid
CROSS APPLY sys.dm_exec_sql_text(er.sql_handle) AS qt
WHERE session_id > 50 -- Ignore system spids.
AND session_id NOT IN ( @@SPID ) -- Ignore this current statement.
ORDER BY 1 ,
2
--删除解锁
KILL 1000 --spid
查询前 10 个可能是性能最差的 SQL 语句
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"
,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
查询逻辑读取最高的sql
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
查询索引碎片
--创建变量 指定要查看的表
declare @table_id int
set @table_id=object_id('TableName')
--执行
dbcc showcontig(@table_id)
Logical Scan Fragmentation-逻辑扫描碎片：该百分比应该在0％到10％之间，高了则说明有外部碎片。
Extent Scan Fragmentation-扩展盘区扫描碎片：该百分比应该是0％，高了则说明有外部碎片。
扫描密度［最佳值:实际值］：该百分比应该尽可能靠近100％。低了则说明有外部碎片。
查询未使用过的索引
SELECT 'SQL Server Instance Start with ' + CONVERT(VARCHAR(16),create_date,120) FROM sys.databases
WHERE database_id =2;
SELECT DB_NAME(diu.database_id) AS DatabaseName ,
s.name +'.' +QUOTENAME(o.name) AS TableName ,
i.index_id AS IndexID ,
i.name AS IndexName ,
CASE WHEN i.is_unique =1 THEN 'UNIQUE INDEX'
ELSE 'NOT UNIQUE INDEX' END AS IS_UNIQUE,
CASE WHEN i.is_disabled=1 THEN 'DISABLE'
ELSE 'ENABLE' END AS IndexStatus,
o.create_date AS IndexCreated,
STATS_DATE(o.object_id,i.index_id) AS StatisticsUpdateDate,
diu.user_seeks AS UserSeek ,
diu.user_scans AS UserScans ,
diu.user_lookups AS UserLookups ,
diu.user_updates AS UserUpdates ,
p.TableRows ,
'DROP INDEX ' + QUOTENAME(i.name)
+ ' ON ' + QUOTENAME(s.name) + '.'
+ QUOTENAME(OBJECT_NAME(diu.object_id)) +';' AS 'Drop Index Statement'
FROM sys.dm_db_index_usage_stats diu
INNER JOIN sys.indexes i ON i.index_id = diu.index_id
AND diu.object_id = i.object_id
INNER JOIN sys.objects o ON diu.object_id = o.object_id
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id
INNER JOIN ( SELECT SUM(p.rows) TableRows ,
p.index_id ,
p.object_id
FROM sys.partitions p
GROUP BY p.index_id ,
p.object_id
) p ON p.index_id = diu.index_id
AND diu.object_id = p.object_id
WHERE OBJECTPROPERTY(diu.object_id, 'IsUserTable') = 1
AND diu.database_id = DB_ID()
AND i.is_primary_key = 0 --排除主键索引
AND i.is_unique_constraint = 0 --排除唯一索引
AND diu.user_updates <> 0 --排除没有数据变化的索引
AND diu.user_lookups = 0
AND diu.user_seeks = 0
AND diu.user_scans = 0
AND i.name IS NOT NULL --排除那些没有任何索引的堆表
ORDER BY ( diu.user_seeks + diu.user_scans + diu.user_lookups ) ASC,diu.user_updates DESC;
GO