C# 具有Linq性能问题的EntityFramework 6.1.1
我正在使用EntityFramework从mssql数据库中选择数据。我的查询如下所示:C# 具有Linq性能问题的EntityFramework 6.1.1,c#,sql-server,linq,entity-framework,C#,Sql Server,Linq,Entity Framework,我正在使用EntityFramework从mssql数据库中选择数据。我的查询如下所示: int param = 123456; using (var context = new DatabaseContext()) { var query = context.Table.AsQueryable(); var result = query.Where(o => o.Id == param).ToList(); } 此查询大约需要10秒钟 using (var contex
int param = 123456;
using (var context = new DatabaseContext())
{
var query = context.Table.AsQueryable();
var result = query.Where(o => o.Id == param).ToList();
}
此查询大约需要10秒钟
using (var context = new DatabaseContext())
{
var query = context.Table.AsQueryable();
var result = query.Where(o => o.Id == 123456).ToList();
}
此查询不到1秒
我刚刚发现EntityFramework生成两个不同的查询
问题1:
SELECT TOP (20)
[Project1].[Id] AS [Id],
[Project1].[Name] AS [Name],
FROM ( SELECT [Project1].[Id] AS [Id], [Project1].[Name] AS [Name], row_number() OVER (ORDER BY [Project1].[Id] DESC) AS [row_number]
FROM ( SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Name] AS [Name]
FROM [dbo].[Table] AS [Extent1]
WHERE [Extent1].[Id] = @p__linq__0
) AS [Project1]
) AS [Project1]
WHERE [Project1].[row_number] > 0
ORDER BY [Project1].[Id] DESC
-- p__linq__0: '2932323' (Type = Int32, IsNullable = false)
问题2:
SELECT TOP (20)
[Filter1].[Id] AS [Id],
[Filter1].[Name] AS [Name]
FROM ( SELECT [Extent1].[Id] AS [Id], [Extent1].[Name] AS [Name], row_number() OVER (ORDER BY [Extent1].[Id] DESC) AS [row_number]
FROM [dbo].[Table] AS [Extent1]
WHERE 2932323 = [Extent1].[Id]
) AS [Filter1]
WHERE [Filter1].[row_number] > 0
ORDER BY [Filter1].[Id] DESC
有没有一种方法可以加快第一种或另一种方法的速度?imho,看到sql查询,这不仅是一个与EF相关的性能问题,而且是一个sql server性能问题 你应该考虑以下几点:
- 由于Id不是PK:在其上创建索引李>
- 使用
更新统计信息并帮助db服务器生成更好的执行计划EXEC sp_updatestats
p.能否显示为每个查询生成的查询?另外,为什么不直接查询
上下文
?为什么要使用AsQueryable()
?AsQueryable()
在这两者中都是多余的cases@haim770冗余,是的,但没有问题或有害。带int参数的一个将成为func而不是另一个表达式,你确定吗?并且查询仍然不同?带参数的查询速度仍然较慢,因为EF生成的查询仍然相同。但两者所用的时间相同