小编Kie*_*ron的帖子

我们已经开始使用NuGet的Microsoft.AspNet.Providers.Core包中提供的更新的System.Web.Providers.我们开始迁移现有用户,发现性能下降,然后发生死锁.这个用户少于30,000(远远低于我们需要创建的1,000,000+用户).当我们调用提供程序时,它来自每个服务器上的多个线程,并且有多个服务器运行此相同的进程.这是为了能够尽快创建我们所需的所有用户,并模拟我们期望在其上线时看到的负载.

SQL Server为死锁生成的日志包含以下EF生成的sql:

SELECT
    [Limit1].[UserId] AS [UserId]
  , [Limit1].[ApplicationId] AS [ApplicationId]
  , [Limit1].[UserName] AS [UserName]
  , [Limit1].[IsAnonymous] AS [IsAnonymous]
  , [Limit1].[LastActivityDate] AS [LastActivityDate]
FROM
    (SELECT TOP (1)
        [Extent1].[UserId] AS [UserId]
      , [Extent1].[ApplicationId] AS [ApplicationId]
      , [Extent1].[UserName] AS [UserName]
      , [Extent1].[IsAnonymous] AS [IsAnonymous]
      , [Extent1].[LastActivityDate] AS [LastActivityDate]
     FROM
        [dbo].[Users] AS [Extent1]
        INNER JOIN [dbo].[Applications] AS [Extent2] ON [Extent1].[ApplicationId] = [Extent2].[ApplicationId]
     WHERE
        ((LOWER([Extent2].[ApplicationName])) = (LOWER(@p__linq__0)))
        AND ((LOWER([Extent1].[UserName])) = (LOWER(@p__linq__1)))
    ) AS [Limit1]

我们手动运行查询,执行计划表示它正在执行表扫描,即使存在基础索引.原因是使用LOWER([Extent1].[UserName]).

我们查看了提供程序代码,看看我们是否做错了什么,或者是否有办法拦截或替换数据库访问代码.我们没有看到任何选项来执行此操作,但我们确实找到了LOWER问题的根源,.ToLower()正在调用列和参数.

return (from …