sql server 性能优化方法
一、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') )
二、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
三、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
where database_id=db_id('数据库名称') --指定数据库
and object_name(a.object_id) not like 'sys%'
and object_name(a.object_id) like '表名' --指定索引表
and b.name is not null
--and b.name like '索引名' --指定索引名称 可以先使用 sp_help '你的表名' 查看表的结构和所有的索引信息
group by db_name(database_id) ,
object_name(a.object_id),
b.name,
user_seeks ,
user_scans
order by user_seeks,user_scans,object_name(a.object_id)
四、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
五、 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。
六、修改索引填充因子（FILLFACTOR：填充因子,ONLINE:ON 重建索引时表仍然可以正常使用）
--修改表下所有索引填充因子
ALTER INDEX ALL ON TableName REBUILD WITH (FILLFACTOR=90,ONLINE=ON)
--修改表下指定索引填充因子
ALTER INDEX indexName ON TableName REBUILD WITH (FILLFACTOR = 80);
七、查询未使用过的索引
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
八、查询表下索引使用情况
select db_name(database_id) as N'数据库名称',
object_name(a.object_id) as N'表名',
b.name N'索引名称',
user_seeks N'用户索引查找次数',
user_scans N'用户索引扫描次数',
max(last_user_seek) N'最后查找时间',
max(last_user_scan) N'最后扫描时间',
max(rows) as N'表中的行数'
from sys.dm_db_index_usage_stats a join
sys.indexes b
on a.index_id = b.index_id
and a.object_id = b.object_id
join sysindexes c
on c.id = b.object_id
where database_id=db_id('数据库名称') --指定数据库
and object_name(a.object_id) not like 'sys%'
and object_name(a.object_id) like '表名' --指定索引表
and b.name is not null
--and b.name like '索引名' --指定索引名称 可以先使用 sp_help '你的表名' 查看表的结构和所有的索引信息
group by db_name(database_id) ,
object_name(a.object_id),
b.name,
user_seeks ,
user_scans
order by user_seeks,user_scans,object_name(a.object_id)
九、查询表结构信息
SELECT 表名 = CASE WHEN a.colorder = 1 THEN d.name
ELSE ''
END ,
表说明 = CASE WHEN a.colorder = 1 THEN ISNULL(f.value, '')
ELSE ''
END ,
字段序号 = a.colorder ,
字段名 = a.name ,
标识 = CASE WHEN COLUMNPROPERTY(a.id, a.name, 'IsIdentity') = 1
THEN '√'
ELSE ''
END ,
主键 = CASE WHEN EXISTS ( SELECT 1
FROM sysobjects
WHERE xtype = 'PK'
AND parent_obj = a.id
AND name IN (
SELECT name
FROM sysindexes
WHERE indid IN (
SELECT
indid
FROM sysindexkeys
WHERE id = a.id
AND colid = a.colid ) ) )
THEN '√'
ELSE ''
END ,
类型 = b.name ,
占用字节数 = a.length ,
长度 = COLUMNPROPERTY(a.id, a.name, 'PRECISION') ,
小数位数 = ISNULL(COLUMNPROPERTY(a.id, a.name, 'Scale'), 0) ,
允许空 = CASE WHEN a.isnullable = 1 THEN '√'
ELSE ''
END ,
默认值 = ISNULL(e.text, '') ,
字段说明 = ISNULL(g.[value], '')
FROM syscolumns a
LEFT JOIN systypes b ON a.xusertype = b.xusertype
INNER JOIN sysobjects d ON a.id = d.id
AND d.xtype = 'U'
AND d.name <> 'dtproperties'
LEFT JOIN syscomments e ON a.cdefault = e.id
LEFT JOIN sys.extended_properties g ON a.id = G.major_id
AND a.colid = g.minor_id
LEFT JOIN sys.extended_properties f ON d.id = f.major_id
AND f.minor_id = 0
WHERE d.name = 'TableName' --如果只查询指定表,加上此红色where条件，tablename是要查询的表名；去除红色where条件查询说有的表信息
ORDER BY a.id ,
a.colorder
