BatchSaveChanges should support operation.AllowConcurrency = false

[jzabroski]

Description

When saving data to tables with audit logs (temporal tables), using BatchSaveChanges, ZZZ Projects uses ValidFrom/ValidTo/Version columns to determine optimistic concurrency behavior. In practice, since the table is audit logged, any over-written changes would be easy to see in the audit log. Moreover, while BulkSaveChanges does allow this, calling BulkSave generates a MERGE statement that can fail when there is a non-clustered index on the temporal table (this failure is a long-standing issue with SQL Server dating back to SQL Server 2008 pre-R2 that has had various fixes, and currently doesnt work for temporal tables in practice, as almost any useful temporal table will have a non-clustered index on the main table's primary key for navigation purposes). Hence, it would be ideal to have feature parity with BulkSaveChanges operation.AllowConcurrency = false

Currently, I can't write code like this:

try
{
    // DbContext.Entry calls detect changes which becomes when the change tracker is tracking a large number of entities.
    // To avoid this performance issue we will:
    //   * Disable change tracking
    //   * Call detect changes to ensure everything is up to date
    //   * Do our state changes
    //   * Turn back on change tracking
    // We know can do this safely as EF won't modify the state of entity (see Rule 1): 
    // https://blog.oneunicorn.com/2012/03/12/secrets-of-detectchanges-part-3-switching-off-automatic-detectchanges/

    Context.Configuration.AutoDetectChangesEnabled = false;
    Context.ChangeTracker.DetectChanges();
    foreach (var entity in entities)
    {
        var entry = Context.Entry(entity);
        if (entry.State == EntityState.Detached)
        {
            entry.State = entity.IsTransient() ? EntityState.Added : EntityState.Modified;
        }
    }
}
finally
{
    Context.Configuration.AutoDetectChangesEnabled = true;
}
Context.UnderlyingContext.BulkSaveChanges(operation =>
{
    operation.AllowConcurrency = false;
});

The above example will hit System.Data.SqlClient.SqlException: Attempting to set a non-NULL-able column's value to NULL.

I want to write code like this:

try
{
    // DbContext.Entry calls detect changes which becomes when the change tracker is tracking a large number of entities.
    // To avoid this performance issue we will:
    //   * Disable change tracking
    //   * Call detect changes to ensure everything is up to date
    //   * Do our state changes
    //   * Turn back on change tracking
    // We know can do this safely as EF won't modify the state of entity (see Rule 1): 
    // https://blog.oneunicorn.com/2012/03/12/secrets-of-detectchanges-part-3-switching-off-automatic-detectchanges/

    Context.Configuration.AutoDetectChangesEnabled = false;
    Context.ChangeTracker.DetectChanges();
    foreach (var entity in entities)
    {
        var entry = Context.Entry(entity);
        if (entry.State == EntityState.Detached)
        {
            entry.State = entity.IsTransient() ? EntityState.Added : EntityState.Modified;
        }
    }
}
finally
{
    Context.Configuration.AutoDetectChangesEnabled = true;
}
Context.UnderlyingContext.BatchSaveChanges(operation =>
{
    operation.AllowConcurrency = false;
});

Exception

System.Data.Entity.Infrastructure.DbUpdateConcurrencyException: Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=472540 for information on understanding and handling optimistic concurrency exceptions. ---> System.Data.Entity.Core.OptimisticConcurrencyException: Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=472540 for information on understanding and handling optimistic concurrency exceptions. at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.ValidateRowsAffected(Int64 rowsAffected, UpdateCommand source) at Z.EntityFramework.Extensions.PolyCommandSet.Execute() at ?.?(Action1 ?) --- End of inner exception stack trace --- at ?.?(Action1 ?)

Further technical details

• EF version: [EF Classic 6 v6.4.4]
• EF Extensions version: [EFE Core v7.18.4]
• Database Server version: [SQL Server 2019]
• Database Provider version (NuGet): [latest .NET 4.8 System.Data dependency]