Linq to sql 简单性能差异指引-技术开发专区

Linq to sql 简单性能差异指引

作者：ITPUB论坛编辑： nancy 2008-04-28 00:00

【IT168技术文档】

禁用ObjectTrackingEnabled
当只是查询数据而不跟踪对象状态时禁用，将极大的提供查询性能。性能差异在36倍左右。测试代码：

 AdventureWorksDataContext adventureWorks1 = new AdventureWorksDataContext();
DateTime d1 = DateTime.Now;
adventureWorks1.ObjectTrackingEnabled = true;
var q1 = (from p in adventureWorks1.Products select p).ToList();
DateTime d2 = DateTime.Now;
Console.WriteLine(d2.Ticks - d1.Ticks);
AdventureWorksDataContext adventureWorks2 = new AdventureWorksDataContext();
DateTime d3 = DateTime.Now;
adventureWorks2.ObjectTrackingEnabled = false;
var q2 = (from p in adventureWorks2.Products select p).ToList();
DateTime d4 = DateTime.Now;
Console.WriteLine(d4.Ticks - d3.Ticks);

不记录输出
输入记录一般只用在开发阶段，在部署环境中一般不使用。性能差异在17-18倍左右。测试代码：

AdventureWorksDataContext adventureWorks1 = new AdventureWorksDataContext();
DateTime d1 = DateTime.Now;
adventureWorks1.Log = Console.Out;
var q1 = (from p in adventureWorks1.Products select p).ToList();
DateTime d2 = DateTime.Now;
Console.WriteLine(d2.Ticks - d1.Ticks);
AdventureWorksDataContext adventureWorks2 = new AdventureWorksDataContext();
DateTime d3 = DateTime.Now;
var q2 = (from p in adventureWorks2.Products select p).ToList();
DateTime d4 = DateTime.Now;
Console.WriteLine(d4.Ticks - d3.Ticks);

编译lambda表达式
性能差异14-15倍。测试代码：

AdventureWorksDataContext adventureWorks1 = new AdventureWorksDataContext();
DateTime d1 = DateTime.Now;
var q1 = (from p in adventureWorks1.Products select p).ToList();
DateTime d2 = DateTime.Now;
Console.WriteLine(d2.Ticks - d1.Ticks);
AdventureWorksDataContext adventureWorks2 = new AdventureWorksDataContext();
DateTime d3 = DateTime.Now;
var compiledQuery = CompiledQuery.Compile((AdventureWorksDataContext ctx) => from p in ctx.Products select p);
var q2 = compiledQuery(adventureWorks2).ToList();
DateTime d4 = DateTime.Now;
Console.WriteLine(d4.Ticks - d3.Ticks);

使用DataLoadOptions.LoadWith
性能差异5-6倍左右。测试代码：

AdventureWorksDataContext adventureWorks1 = new AdventureWorksDataContext();
DateTime d1 = DateTime.Now;
var q1 = (from o in adventureWorks1.WorkOrders where o.ProductID == 3 select o).ToList();
DateTime d2 = DateTime.Now;
Console.WriteLine(d2.Ticks - d1.Ticks);
AdventureWorksDataContext adventureWorks2 = new AdventureWorksDataContext();
DateTime d3 = DateTime.Now;
DataLoadOptions options = new DataLoadOptions();
options.LoadWith<WorkOrder>(o => o.Product);
adventureWorks2.LoadOptions = options;
var q2 = (from o in adventureWorks2.WorkOrders where o.ProductID == 3 select o).ToList();
DateTime d4 = DateTime.Now;
Console.WriteLine(d4.Ticks - d3.Ticks);

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