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HomeDatabaseMysql TutorialSQL Server插入或者批量导入大量数据的性能表现

我经常看到客户测试SQL Server 的插入(INSERT)或者批量导入大量数据的性能表现。其中有测试大量INSERT的TSQL脚本如下: use myDB go create table t1 ( id int primary key not null identity ( 1 , 1 ), name varchar ( 200 ), memo char ( 500 )); go trun

我经常看到客户测试SQL Server 的插入(INSERT)或者批量导入大量数据的性能表现。其中有测试大量INSERT的TSQL脚本如下:

use myDB

go

createtable t1(id intprimarykeynotnullidentity (1,1),name varchar(200),memo char(500));

go

truncatetable t1

go

declare @i int

set @i=0

declare @beginTime datetime,@endTime datetime

set @beginTime=GETDATE()

while(@i200000)

begin

 insertinto t1(name,memo)values('test'+str(RAND()*100000000),'memo'+str(RAND()*100000000))

 set @i=@i+1

end

set @endTime=GETDATE()

select @endTime-@beginTime

上面这个脚本测试插入200000行数据需要的时间。这个脚本有问题么?

语法没有问题,但是写法却不够优化。如果你使用performance  monitor

来观察,就会发现在数据插入期间log flushes/sec的次数非常高。在我的机器上达到5000。Log flushes发生一次,意味着SQL server 需要写入事务日志(transaction log)一次。每秒5000次的日志写动作导致磁盘大量的写操作。正是这个磁盘写操作影响了上面的batch的性能。我上面脚本在我的机器上使用了大概40秒左右的时间。

如何改进这个脚本的性能呢?如何减少log flushes/sec从而减少磁盘的写操作? 答案是使用Batch Size如下面脚本所示。

truncatetable t1

go

declare @i int

set @i=0

declare @beginTime datetime,@endTime datetime

set @beginTime=GETDATE()

declare @batchSize int

set @batchSize=1000

while(@i00000)

begin

 if (@i%@batchSize=0)

    begin

      if (@@TRANCOUNT>0)COMMITTRAN

      BEGINTRAN

    end

   

 insertinto t1(name,memo)values('test'+str(RAND()*100000000),'memo'+str(RAND()*100000000))

 set @i=@i+1

end

 if (@@TRANCOUNT>0)COMMITTRAN

set @endTime=GETDATE()

select @endTime-@beginTime

黄色高亮是我改进的地方。我在同样的机器上跑了一下,奇迹发生了,它只使用了7秒多一点。快了5倍多!如果在看下performance

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