What's the reason/logic behind a redundant update (update [Table] set @p = 0 where ...)

Question

Hello,
I've seen EF4 do what seems to be a redundant update command that I'm curious why it does that.
Take a look at Julie Lerman's Blog post on EF Table Splitting (http://thedatafarm.com/blog/data-access/ef-table-splitting-ndash-the-opposite-of-entity-splitting/).

In her SQL Profiler trace she has this command executed:

exec sp_executesql N'declare @p int
update [SalesLT].[SalesOrderHeader]
set @p = 0
where ([SalesOrderID] = @0)
select [SalesOrderNumber], [TotalDue]
from [SalesLT].[SalesOrderHeader]
where @@ROWCOUNT > 0 and [SalesOrderID] = @0',N'@0 int',@0=71774

What's the logic behind the update command, that is not updating any value?

Thanks,
Aviv.

Answer 1

We are having our Entity Framework 4 sessions fail, and it seems that these redundant updates are the cause.  The undesired updates are forcing our _VERSION timestamp to be incremented and then we are receiving concurrency update errors - even on a local database with only one user testing.  This has us really dismayed and disappointed.  Why is this happening?

System.Data.OptimisticConcurrencyException was unhandled by user code
  Message=Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.
  Source=System.Data.Entity
  StackTrace:
       at System.Data.Mapping.Update.Internal.UpdateTranslator.ValidateRowsAffected(Int64 rowsAffected, UpdateCommand source)
       at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)
       at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache)
       at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
       at System.Data.Objects.ObjectContext.SaveChanges()
       at PwC.NDF.Data.EntityFramework.EntityFrameworkDAO`2.GetEntityKey(E domain)
       at PwC.NDF.Data.EntityFramework.EntityFrameworkDAO`2.GetID(E domain)

 

 

Answer 2

I have the same problem.  Did you find a solution?