如何防止 SQL 服务器存储过程中的死锁？

Question

我正在调用一个存储过程，该过程执行 INSERT 或 UPDATE 取决于 table 中存在的过程键。

到目前为止，程序按预期运行。直到我们的用户群开始扩大。今天我收到以下错误，通过重新启动应用程序池运行服务解决了该错误：

InsertDDM_UserDashboard error: RequestError: Transaction (Process ID 64) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.

我查看了 this link，这表明它可能是 SELECT 和 UPDATE 运行ning 同时导致死锁的问题。但是我的程序用 IF..ELSE 条件将语句分开，因此两者不能同时运行。

存储过程：

SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON
GO

ALTER PROCEDURE [dbo].[InsertDDM_UserDashboard]
   @p_email VARCHAR(255),
   @p_dashboardPreferences VARCHAR(4000),
   @p_userDefaultDashboard VARCHAR(500)
AS 

IF (NOT EXISTS(SELECT * FROM [dbo].[DDM_UserProfile] WHERE Email = @p_email)) 
BEGIN    

    INSERT INTO [dbo].[DDM_UserProfile]
           ([Email]
           ,[DashboardPreferences]
           ,DefaultDashboard
           )
     VALUES
           (@p_email
           ,@p_dashboardPreferences
           ,@p_userDefaultDashboard
           )

END ELSE BEGIN

        UPDATE [dbo].[DDM_UserProfile]
        SET [DashboardPreferences]=@p_dashboardPreferences
        WHERE [Email]=@p_email

        UPDATE [dbo].[DDM_UserProfile]
        SET DefaultDashboard=@p_userDefaultDashboard
        WHERE [Email]=@p_email

END

Answer 1

需要查看 table 和索引 DDL 以及完整的死锁图才能确定，但您可能只需要在初始读取时锁定目标行。 EG

ALTER PROCEDURE [dbo].[InsertDDM_UserDashboard]
   @p_email VARCHAR(255),
   @p_dashboardPreferences VARCHAR(4000),
   @p_userDefaultDashboard VARCHAR(500)


AS 
begin
begin transaction

IF (NOT EXISTS(SELECT * FROM [dbo].[DDM_UserProfile] with (updlock, holdlock) WHERE Email = @p_email)) 
BEGIN     
INSERT INTO [dbo].[DDM_UserProfile]
        ([Email]
        ,[DashboardPreferences]
        ,DefaultDashboard
        )
    VALUES
        (@p_email
        ,@p_dashboardPreferences
        ,@p_userDefaultDashboard
        )

END

ELSE 
BEGIN 
    UPDATE [dbo].[DDM_UserProfile]
    SET [DashboardPreferences]=@p_dashboardPreferences,
        DefaultDashboard=@p_userDefaultDashboard
    WHERE [Email]=@p_email

END

commit transaction
end

Answer 2

您可以像这样使用 Sam Saffron upsert approach：

create procedure dbo.ddm_UserProfile_Dashboard_upsert (
    @p_email varchar(255)
  , @p_dashboardPreferences varchar(4000)
  , @p_userDefaultDashboard varchar(500)
) as 
begin
  set nocount, xact_abort on;
  begin tran;
    update up
      set DashboardPreferences=@p_dashboardPreferences
        , DefaultDashboard    =@p_userDefaultDashboard
      from  dbo.ddm_UserProfile up with (serializable) 
      where up.Email = @p_email;
    if @@rowcount = 0
    begin;
      insert into dbo.ddm_UserProfile (Email, DashboardPreferences, DefaultDashboard)
      values (@p_email, @p_dashboardPreferences, @p_userDefaultDashboard);
    end;
  commit tran;
end;
go

如何防止 SQL 服务器存储过程中的死锁？

How to prevent deadlock in SQL Server stored procedure?

sql-server

deadlock

stored-procedures

transactions