SqlServer性能优化 即席查询（十三）
执行计划，查询类别：
1.即席查询 2.预定义查询
select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.Size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=
c.ProductCategoryKey where p.Size>'1'
--查询执行计划是否被缓存
select c.usecounts,c.size_in_bytes,c.objtype,t.text from sys.dm_exec_cached_plans as c
cross apply sys.dm_exec_sql_text(c.plan_handle) as t dbcc freeproccache--清空执行计划
--没有join 的形式会生成简单参数化
select EnglishProductName,Color,Size from Product where size>'1'--简单参数化 select EnglishProductName,Color,Size from Product where size>'2'--简单参数化
select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.Size
from Product as p inner join ProductCategory as c on p.aProductSubcategoryKey=
c.ProductCategoryKey where p.Size>'2'
语句一样时即席查询才会重用执行计划。
优化：打开开关
exec sp_configure 'show advanced options',1
reconfigure with override
为ad hoc的查询优化：
exec sp_configure 'Optimize for ad hoc workloads',1
reconfigure with override
--使用参数化
alter database HRDB
set Parameterization forced
set Parameterization forced 强制参数化（like无法识别 ）
select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.Size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=
c.ProductCategoryKey where p.Size>'2' select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.Size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=
c.ProductCategoryKey where p.Size like '2%'
预定义查询：
预定义查询--参数化执行计划：
存储过程：
1.创建时延时检查
2.第一次执行时编译并生成执行计划
3.减少网络传输量
4.封装变化点
5.增强安全性，隔离访问控制
创建存储过程：
create procedure p_querycp @size varchar(500)
as
select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=c.ProductCategoryKey
where p.Size>@size
做跟踪(以前有对应得截图)：
执行存储过程：
create procedure p_querycp @size varchar(500)
as
select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=c.ProductCategoryKey
where p.Size>@size --清空执行计划
dbcc freeproccache
--执行
exec p_querycp '1'
执行重复的语句：
dbcc freeproccache exec p_querycp @size='1' exec p_querycp @size='2'
查看缓存计划：
select c.usecounts,c.size_in_bytes,c.objtype,t.text from sys.dm_exec_cached_plans as c
cross apply sys.dm_exec_sql_text(c.plan_handle) as t
预定义查询---参数化执行计划：
SP_ExecuteSql
避免了自己维护存储过程管理成本
可重用执行计划
Unicode字符串作为参数值与类型
大小写敏感
把存储过程定义成传递参数的：
declare @sqltext nvarchar(500)
set @sqltext=N'
select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=c.ProductCategoryKey
where p.Size>@size
'
declare @params nvarchar(500)
set @params=N'@size varchar(500)'
exec sp_executesql @sqltext,@params,@size='1'
把size 的大小换成 2
在.net中调用：（两种写法）
public object getCp(string size)
{
HRUser dbcontext = new HRUser();
var cps = from p in dbcontext.Product
join c in dbcontext.ProductCategory
on p.ProductSubcategoryKey equals c.ProductCategoryKey
where p.Size == size
//返回匿名对象
select new
{
CName = c.EnglishProductCategoryName,
PName = p.EnglishProductName,
Color = p.Color,
Size = p.Size
};
return cps.ToList();
}
public object getcp(string size)
{
HRUser dbcontext = new HRUser();
var cps = dbcontext.Product.Join(dbcontext.ProductCategory, a => a.ProductSubcategoryKey, ar => ar.ProductCategoryKey, (a, ar) => new
{
CName = ar.EnglishProductCategoryName,
PName = a.EnglishProductName,
Color = a.Color,
Size = a.Size
}).Where(p => p.Size == size);
return cps.ToList();
}
页面：
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="显示产品" />
<asp:GridView ID="GridView1" runat="server">
</asp:GridView>
点击后的事件：
protected void Button2_Click(object sender, EventArgs e)
{
Product p = new Product();
var cps = p.getCp(TextBox1.Text.Trim());
GridView1.DataSource = cps;
GridView1.DataBind();
}
--动态构建语句（执行带参数的方法）
declare @size varchar(500)
set @size='2'
execute('select c.EnglishProductCategoryName,p.EnglishProductName,p.Color,p.size
from Product as p inner join ProductCategory as c on p.ProductSubcategoryKey=c.ProductCategoryKey
where p.Size>'+''''+@size+'''')
dbcc freeproccache --执行计划 缓存
select c.usecounts,c.size_in_bytes,c.objtype,t.text from sys.dm_exec_cached_plans as c
cross apply sys.dm_exec_sql_text(c.plan_handle) as t
形成两个缓存计划：
创建存储过程：
create procedure p_querye @vacationhours int
as
select e.LoginID,e.JobTitle from EmployeeOp as e where VacationHours>@vacationhours
exec p_querye 2--实际执行计划 表扫描 exec p_querye 99--实际执行计划 表扫描 应用用索引更好
--重新编译的执行计划
exec p_querycp 99 with recompile
手工的指定执行几乎：
--手工的指定执行计划
exec sp_create_plan_guide @name='执行任务计划指南之EmployeeOp Vacation',
--转成Unicode编码格式
@stmt=N'select e.LoginID,e.JobTitle from EmployeeOp as e where VacationHours>@vacationhours',
@type=N'Object',
--执行计划的名字
@module_or_batch ='p_querye',
@params =null,
--提示
@hints =N'OPTION(OPTIMIZE FOR(@vacationhours=''99''))'
清除执行计划：执行（会参考上面指定的执行计划）
exec p_querye 2
存储过程重编译：
临时结果集：
定义跟踪的模板：
一：使用物理表进行临时结果集
--1.做一张物理表
create procedure p_physicaltb
as
CREATE TABLE PhysicalTB(
[SalesOrderID] [int] NOT NULL,
[SalesOrderDetailID] [int] NOT NULL,
[CarrierTrackingNumber] [nvarchar](25) NULL,
[OrderQty] [smallint] NOT NULL,
[ProductID] [int] NOT NULL,
[SpecialOfferID] [int] NOT NULL,
[UnitPrice] [money] NOT NULL,
[UnitPriceDiscount] [money] NOT NULL,
[LineTotal] [numeric](38, 6) NOT NULL,
[rowguid] [uniqueidentifier] NOT NULL,
[ModifiedDate] [datetime] NOT NULL
)
insert into PhysicalTB select * from OrderDetail
select * from PhysicalTB set statistics time on
exec p_physicaltb --cpu:391 total:1762
set statistics time off
跟踪的情况：
删除之后再次创建执行。
物理表每次执行都会有重编译的过程（不建议使用物理表来存储临时结果集）
第二种方式：
临时表存储临时结果集
create procedure p_temptb
as
CREATE TABLE #PhysicalTB(
[SalesOrderID] [int] NOT NULL,
[SalesOrderDetailID] [int] NOT NULL,
[CarrierTrackingNumber] [nvarchar](25) NULL,
[OrderQty] [smallint] NOT NULL,
[ProductID] [int] NOT NULL,
[SpecialOfferID] [int] NOT NULL,
[UnitPrice] [money] NOT NULL,
[UnitPriceDiscount] [money] NOT NULL,
[LineTotal] [numeric](38, 6) NOT NULL,
[rowguid] [uniqueidentifier] NOT NULL,
[ModifiedDate] [datetime] NOT NULL
)
insert into #PhysicalTB select * from OrderDetail
select * from #PhysicalTB
drop table #PhysicalTB set statistics time on
exec p_temptb --cpu:110 total:1494
set statistics time off sp_helpdb 'tempdb'--16064,768
第一次执行时重新编译，第二次就不会重新编译了。
用到了tempdb临时表：
第三种方式：表变量存储临时结果集
--表变量存储临时结果集
create procedure p_tabletb
as
--申明表变量
declare @PhysicalTB table(
[SalesOrderID] [int] NOT NULL,
[SalesOrderDetailID] [int] NOT NULL,
[CarrierTrackingNumber] [nvarchar](25) NULL,
[OrderQty] [smallint] NOT NULL,
[ProductID] [int] NOT NULL,
[SpecialOfferID] [int] NOT NULL,
[UnitPrice] [money] NOT NULL,
[UnitPriceDiscount] [money] NOT NULL,
[LineTotal] [numeric](38, 6) NOT NULL,
[rowguid] [uniqueidentifier] NOT NULL,
[ModifiedDate] [datetime] NOT NULL
)
insert into @PhysicalTB select * from OrderDetail
select * from @PhysicalTB set statistics time on
exec p_tabletb --cpu:110 total:1494
set statistics time off sp_helpdb 'tempdb'--17064,768
执行时不会重新编译
第四种方式：
--CTE(通用表表达式)存储临时结果集 完全放在内存中 不会操作任何数据库中的东西
create procedure p_ctetb
as
begin
--会自动推断数据类型
;with PhysicalTB(
[SalesOrderID],
[SalesOrderDetailID],
[CarrierTrackingNumber],
[OrderQty] ,
[ProductID],
[SpecialOfferID],
[UnitPrice] ,
[UnitPriceDiscount] ,
[LineTotal] ,
[rowguid] ,
[ModifiedDate]
) as (select * from OrderDetail)
--访问通用表表达式
select * from PhysicalTB
end
跟踪的结果：
没有重新编译的过程，纯粹操作内存。tempdb数据库不会有任何的变化。
set statistics time on
exec p_ctetb --cpu:100 total:1300
set statistics time off sp_helpdb 'tempdb'--17064,768
高版本的通用表达式可以进行多次的使用：
create procedure p_ctetb1
as
begin
;with PhysicalTB(
[SalesOrderID],
[SalesOrderDetailID],
[CarrierTrackingNumber],
[OrderQty] ,
[ProductID],
[SpecialOfferID],
[UnitPrice] ,
[UnitPriceDiscount] ,
[LineTotal] ,
[rowguid] ,
[ModifiedDate]
) as (select * from OrderDetail)
select * from PhysicalTB
select * from PhysicalTB
end exec p_ctetb1
08之前的数据库，只要把表达式在创建一次就可以了
临时数据集的优化处理：
优化查询：编译指南。
--清空执行计划
dbcc freeproccache
select * from EmployeeOp where VacationHours>1 option(use plan N'
<ShowPlanXML xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan" Version="1.2" Build="12.0.2000.8">
<BatchSequence>
<Batch>
<Statements>
<StmtSimple StatementText="select * from EmployeeOp where VacationHours>99" StatementId="1" StatementCompId="1" StatementType="SELECT" RetrievedFromCache="true" StatementSubTreeCost="0.00657038" StatementEstRows="1" StatementOptmLevel="FULL" QueryHash="0x7E06C77E90EB9FBB" QueryPlanHash="0x64478FC6152D2A83" StatementOptmEarlyAbortReason="GoodEnoughPlanFound" CardinalityEstimationModelVersion="120" ParameterizedText="(@1 tinyint)SELECT * FROM [EmployeeOp] WHERE [VacationHours]>@1">
<StatementSetOptions QUOTED_IDENTIFIER="true" ARITHABORT="true" CONCAT_NULL_YIELDS_NULL="true" ANSI_NULLS="true" ANSI_PADDING="true" ANSI_WARNINGS="true" NUMERIC_ROUNDABORT="false" />
<QueryPlan CachedPlanSize="40" CompileTime="6" CompileCPU="6" CompileMemory="232">
<MemoryGrantInfo SerialRequiredMemory="0" SerialDesiredMemory="0" />
<OptimizerHardwareDependentProperties EstimatedAvailableMemoryGrant="206857" EstimatedPagesCached="51714" EstimatedAvailableDegreeOfParallelism="2" />
<RelOp NodeId="0" PhysicalOp="Nested Loops" LogicalOp="Inner Join" EstimateRows="1" EstimateIO="0" EstimateCPU="4.18e-006" AvgRowSize="830" EstimatedTotalSubtreeCost="0.00657038" Parallel="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row">
<OutputList>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="BusinessEntityID" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="NationalIDNumber" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="LoginID" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="OrganizationNode" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="OrganizationLevel" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="JobTitle" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="BirthDate" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="MaritalStatus" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="Gender" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="HireDate" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="SalariedFlag" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="VacationHours" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="SickLeaveHours" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="CurrentFlag" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="rowguid" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="ModifiedDate" />
</OutputList>
<NestedLoops Optimized="0">
<OuterReferences>
<ColumnReference Column="Bmk1000" />
</OuterReferences>
<RelOp NodeId="1" PhysicalOp="Index Seek" LogicalOp="Index Seek" EstimateRows="1" EstimateIO="0.003125" EstimateCPU="0.0001581" AvgRowSize="19" EstimatedTotalSubtreeCost="0.0032831" TableCardinality="290" Parallel="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row">
<OutputList>
<ColumnReference Column="Bmk1000" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="VacationHours" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="SickLeaveHours" />
</OutputList>
<IndexScan Ordered="1" ScanDirection="FORWARD" ForcedIndex="0" ForceSeek="0" ForceScan="0" NoExpandHint="0" Storage="RowStore">
<DefinedValues>
<DefinedValue>
<ColumnReference Column="Bmk1000" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="VacationHours" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="SickLeaveHours" />
</DefinedValue>
</DefinedValues>
<Object Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Index="[nc_Employee_vacationsickleave]" IndexKind="NonClustered" Storage="RowStore" />
<SeekPredicates>
<SeekPredicateNew>
<SeekKeys>
<StartRange ScanType="GT">
<RangeColumns>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="VacationHours" />
</RangeColumns>
<RangeExpressions>
<ScalarOperator ScalarString="(99)">
<Const ConstValue="(99)" />
</ScalarOperator>
</RangeExpressions>
</StartRange>
</SeekKeys>
</SeekPredicateNew>
</SeekPredicates>
</IndexScan>
</RelOp>
<RelOp NodeId="3" PhysicalOp="RID Lookup" LogicalOp="RID Lookup" EstimateRows="1" EstimateIO="0.003125" EstimateCPU="0.0001581" AvgRowSize="826" EstimatedTotalSubtreeCost="0.0032831" TableCardinality="290" Parallel="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row">
<OutputList>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="BusinessEntityID" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="NationalIDNumber" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="LoginID" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="OrganizationNode" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="OrganizationLevel" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="JobTitle" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="BirthDate" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="MaritalStatus" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="Gender" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="HireDate" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="SalariedFlag" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="CurrentFlag" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="rowguid" />
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="ModifiedDate" />
</OutputList>
<IndexScan Lookup="1" Ordered="1" ScanDirection="FORWARD" ForcedIndex="0" ForceSeek="0" ForceScan="0" NoExpandHint="0" Storage="RowStore">
<DefinedValues>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="BusinessEntityID" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="NationalIDNumber" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="LoginID" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="OrganizationNode" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="OrganizationLevel" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="JobTitle" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="BirthDate" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="MaritalStatus" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="Gender" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="HireDate" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="SalariedFlag" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="CurrentFlag" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="rowguid" />
</DefinedValue>
<DefinedValue>
<ColumnReference Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" Column="ModifiedDate" />
</DefinedValue>
</DefinedValues>
<Object Database="[HRDB]" Schema="[dbo]" Table="[EmployeeOp]" TableReferenceId="-1" IndexKind="Heap" Storage="RowStore" />
<SeekPredicates>
<SeekPredicateNew>
<SeekKeys>
<Prefix ScanType="EQ">
<RangeColumns>
<ColumnReference Column="Bmk1000" />
</RangeColumns>
<RangeExpressions>
<ScalarOperator ScalarString="[Bmk1000]">
<Identifier>
<ColumnReference Column="Bmk1000" />
</Identifier>
</ScalarOperator>
</RangeExpressions>
</Prefix>
</SeekKeys>
</SeekPredicateNew>
</SeekPredicates>
</IndexScan>
</RelOp>
</NestedLoops>
</RelOp>
<ParameterList>
<ColumnReference Column="@1" ParameterCompiledValue="(99)" />
</ParameterList>
</QueryPlan>
</StmtSimple>
</Statements>
</Batch>
</BatchSequence>
</ShowPlanXML> ') --表扫描 select * from sys.dm_exec_cached_plans
select * from sys.dm_exec_sql_text
select * from sys.dm_exec_query_plan
select * from EmployeeOp where VacationHours>99 -- 索引
select c.plan_handle,p.text from sys.dm_exec_cached_plans as c cross apply sys.dm_exec_sql_text(c.plan_handle) as p select * from sys.dm_exec_query_plan(0x06000A00CD253E14207CA0290200000001000000000000000000000000000000000000000000000000000000)
SqlServer性能优化 即席查询（十三）的更多相关文章
- 03.SQLServer性能优化之---存储优化系列
汇总篇:http://www.cnblogs.com/dunitian/p/4822808.html#tsql 概 述:http://www.cnblogs.com/dunitian/p/60413 ...
- SQLServer性能优化之---数据库级日记监控
上节回顾:https://www.cnblogs.com/dotnetcrazy/p/11029323.html 4.6.6.SQLServer监控 脚本示意:https://github.com/l ...
- 01.SQLServer性能优化之----强大的文件组----分盘存储
汇总篇:http://www.cnblogs.com/dunitian/p/4822808.html#tsql 文章内容皆自己的理解,如有不足之处欢迎指正~谢谢 前天有学弟问逆天:“逆天,有没有一种方 ...
- 02.SQLServer性能优化之---牛逼的OSQL----大数据导入
汇总篇:http://www.cnblogs.com/dunitian/p/4822808.html#tsql 上一篇:01.SQLServer性能优化之----强大的文件组----分盘存储 http ...
- mysql性能优化-慢查询分析、优化索引和配置 （慢查询日志，explain，profile）
mysql性能优化-慢查询分析.优化索引和配置 (慢查询日志,explain,profile) 一.优化概述 二.查询与索引优化分析 1性能瓶颈定位 Show命令 慢查询日志 explain分析查询 ...
- SQLServer性能优化专题
SQLServer性能优化专题 01.SQLServer性能优化之----强大的文件组----分盘存储(水平分库) http://www.cnblogs.com/dunitian/p/5276431. ...
- mysql性能优化-慢查询分析、优化索引和配置
一.优化概述 二.查询与索引优化分析 1性能瓶颈定位 Show命令 慢查询日志 explain分析查询 profiling分析查询 2索引及查询优化 三.配置优化 1) max_connec ...
- [转]mysql性能优化-慢查询分析、优化索引和配置
一. 优化概述 MySQL数据库是常见的两个瓶颈是CPU和I/O的瓶颈,CPU在饱和的时候一般发生在数据装入内存或从磁盘上读取数据时候.磁盘I/O瓶颈发生在装入数据远大于内存容量的时候,如果应用分布在 ...
- mysql性能优化-慢查询分析、优化索引和配置【转】
一.优化概述 二.查询与索引优化分析 1性能瓶颈定位 Show命令 慢查询日志 explain分析查询 profiling分析查询 2索引及查询优化 三.配置优化 1) max_connec ...
随机推荐
- 前端面试题2016--CSS
介绍一下标准的CSS的盒子模型?低版本IE的盒子模型有什么不同的? (1)有两种,IE 盒子模型.W3C 盒子模型:(2)盒模型:内容(content).填充(padding).边界(margin). ...
- LookUpEdit手动编辑怎么设置呢？
近来遇到一问题,用LookUpEdit控件时,无法进行手动删除上面的数据,为此查找资料进行修改: 解决方法如下:LookUpEdit的属性-->Properties->TextEditSt ...
- react验证码倒计时
<!DOCTYPE html> <html> <head> <script src="../build/react.js">< ...
- 5、HTML5列表、块和布局
1.块元素 块元素在显示的时候,通常会以新行开始 如:<h1> <p> <ul> <!-- 块—>注释 <p>hello</p> ...
- Java集合类学习笔记（各种线性表性能分析）
ArrayList.LinkedList是线性表的两种典型实现:基于数组的线性表和基于链的线性表. Queue代表了队列,Deque代表了双端队列. 一般来说,由于数组以一块连续内存区来保存所有的数组 ...
- Git 配置
在 windows 上安装完 Git 会右键菜单中看到 Git 的快捷打开选项, 点 Git Bash Here 就可以在当前目录下打开 Git 的命令行 Git shell,初次使用 Git 先配置 ...
- Object有哪些公用方法
Object是所有类的父类,任何类都默认继承Object.Object类到底实现了哪些方法? 1．clone方法 保护方法,实现对象的浅复制,只有实现了Cloneable接口才可以调用该方法,否则抛出 ...
- XML特殊字符处理
XML共有5个特殊字符,分别为:&<>"' 如果XML文件中需要包含如上5个特殊字符,有两种方式: 1.将包含特殊字符的字符串放在<![CDATA[]]>中 ...
- java开发环境搭建
回顾环境安装的流程. 安装jdk 配置java开发环境 配置path以及classpath. 我是在http://www.oracle.com/上下载的.点击Downloads-->java f ...
- android studio集成融云 SDK 后在部分机型启动对话时崩溃
最初构建项目是 eclipse, 后来切换到 android studio来做开发. 后来多个用户反馈在android4.4机型上存在启动对话崩溃的问题.但是IOS 版工程从来没有重现. 调试报错信息 ...