Linq-to-SQL性能优化提升实践

Linq-to-SQL的性能优化，根据我的个人实践和效果降序排列，如下：

1. 预编译 CompiledQuery （如果执行次数不止一次的话）

/// <summary>

/// Utility class to store compiled queries

/// </summary>

public static class QueriesUtility

{

/// <summary>

/// Gets the query that returns categories with more than five products.

/// </summary>

/// <value>The query containing categories with more than five products.</value>

public static Func<NorthwindDataContext, int, IEnumerable<Category>>

GetCategoriesWithMoreThanFiveProducts

{

get

{

Func<NorthwindDataContext, IEnumerable<Category>> func =

CompiledQuery.Compile<NorthwindDataContext, int, IEnumerable<Category>>

((NorthwindDataContext context, int count) => context.Categories.

Where<Category>(cat => cat.Products.Count > count));

return func;

}

}

}

调用：

using (NorthwindDataContext context = new NorthwindDataContext())

{

QueriesUtility.GetCategoriesWithMoreThanFiveProducts(context, 5);

}

2. 缓存MappingSource

把默认的DataContext用自己的代替，代码如下：

using System;

using System.Data;

using System.Data.Linq;

using System.Data.Linq.Mapping;

namespace My.Company.Depart

{

public class MyDataContext : DataContext

{

/// <summary>

/// Thread-safe

/// Cached MappingSource

/// </summary>

private static MappingSource _cachedMappingSource = new AttributeMappingSource(); /* Thread-safe */

public MyDataContext(IDbConnection cx)

: base(cx, _cachedMappingSource)

{

}

public MyDataContext(string cx, bool ojectTrackingEnabled = true, bool consoleLogging = false)

: base(cx, _cachedMappingSource)

{

this.ObjectTrackingEnabled = ojectTrackingEnabled;

if (consoleLogging)

this.Log = Console.Out;

}

public Table<MyTable> MyTable

{

get { return this.GetTable<MyTable>(); }

}

//blah. blah, blah......

}

}

然后这样调用：

using (var dataContext = new MyDataContext(ConnectionStringProvider.GetDefault()))

{

var list = dataContext.MyTable.Where(t => t.ID > 5).ToList();

//blah. blah, blah......

}

3. 查询的时候关闭ObjectTrackingEnabled

dataContext.ObjectTrackingEnabled = false;

关于ObjectTrackingEnabled更详细的解释查看这个页面。

4. 关联表查询的时候用 LoadOptions

关于Load,LoadWith,AssociateWith查看这个页面

5. 其它参考资料

Speeding up linq-to-sql

10 Tips to Improve your LINQ to SQL Application Performance