NHibernate Schema Export alters wrong tables (possible bug in NH?)

Question

I use NHibernates schema export functionality to create and update the database.

However sometimes (seems to happen on slow machines more frequently) NHibernate generates incorrect alter table scripts. I disabled the schema export and log the statements to debug the problem.

This problem occurs randomly and affects randomly different tables.

An example script is: alter table dbo.VlogNet_NumberGroups add DKS_P03_Artikelgruppe BIGINT

However the "DKS_P03_Artikelgruppe" column belongs to a completely different mapping and to make it worse this mapping is even configured to NHibernate.Mapping.ByCode.SchemaAction.None.

Edit: To clarify my question: Why does NHibernate randomly mix up different mappings and issues alter table commands which break my database.

Mappings:

public class NumberGroupMap : HierachicalEntityMap<NumberGroup>
{
    public NumberGroupMap()
    {
        Property(x => x.StartNumber);
        Property(x => x.EndNumber);
        Property(x => x.LastGeneratedNumber);
        Property(x => x.StartTime);
        Property(x => x.LifeSpan);
        Property(x => x.ResetOnNewYear);
        Property(x => x.IsResetable);
        Property(x => x.WarningAtPos);
    }

    public override string TableName
    {
        get { return "VlogNet_NumberGroups"; }
    }
}

HierachicalEntityMap<T> derives from ClassMapping<T>, it just adds some Properties (ID, Name, Parent) and sets the TableName to the value of the corresponding Property.

The field DKS_P03_Artikelgruppe originates from this mapping:

public class DksCarrierInformationMap : ClassMapping<DksCarrierInformation>
{
    public const string EntityTable = "DKS_Liste";

    public DksCarrierInformationMap()
    {
        Table(EntityTable);
        SchemaAction(NHibernate.Mapping.ByCode.SchemaAction.None);

        Id(x => x.Auto_ID, x => x.Generator(Generators.Identity));
        Property(x => x.Versanddaten_ID, x => { x.NotNullable(true); x.Unique(true); });

        #region Invoiceaddress
        // ... left for brevity
        #endregion

        #region Labelinformationen

        // ... left for brevity

        #endregion

        #region EDI

        // ... left for brevity

        Component(x => x.DKS_P01, x =>
                                      {
                                          x.Property(c => c.Artikelgruppe, c => c.Column("DKS_P01_Artikelgruppe"));
                                          x.Property(c => c.Anz_Teile, c => c.Column("DKS_P01_Anz_Teile"));
                                          x.Property(c => c.Anz_Buegel, c => c.Column("DKS_P01_Anz_Buegel"));
                                          x.Property(c => c.Gewicht, c => c.Column("DKS_P01_Gewicht"));
                                          x.Property(c => c.Type, c => { c.Column("DKS_P01_ArtikelTyp"); c.Type>(); c.Length(10); });
                                          x.Property(c => c.Bezeichnung, c => c.Column("DKS_P01_Bezeichnung"));
                                      });

        // ... left for brevity

        Component(x => x.DKS_P03, x =>
                                      {
                                          x.Property(c => c.Artikelgruppe, c => c.Column("DKS_P03_Artikelgruppe"));
                                          x.Property(c => c.Anz_Teile, c => c.Column("DKS_P03_Anz_Teile"));
                                          x.Property(c => c.Anz_Buegel, c => c.Column("DKS_P03_Anz_Buegel"));
                                          x.Property(c => c.Gewicht, c => c.Column("DKS_P03_Gewicht"));
                                          x.Property(c => c.Type, c => { c.Column("DKS_P03_ArtikelTyp"); c.Type>(); c.Length(10); });
                                          x.Property(c => c.Bezeichnung, c => c.Column("DKS_P03_Bezeichnung"));
                                      });

        // ... left for brevity

        Component(x => x.DKS_P20, x =>
                                      {
                                          x.Property(c => c.Artikelgruppe, c => c.Column("DKS_P20_Artikelgruppe"));
                                          x.Property(c => c.Anz_Teile, c => c.Column("DKS_P20_Anz_Teile"));
                                          x.Property(c => c.Anz_Buegel, c => c.Column("DKS_P20_Anz_Buegel"));
                                          x.Property(c => c.Gewicht, c => c.Column("DKS_P20_Gewicht"));
                                          x.Property(c => c.Type, c => { c.Column("DKS_P20_ArtikelTyp"); c.Type>(); c.Length(10); });
                                          x.Property(c => c.Bezeichnung, c => c.Column("DKS_P20_Bezeichnung"));
                                      });

        #endregion
    }
}

The code which sets up the NHibernate SessionFactory:

var modelMapper = new ModelMapper();
foreach (var assembly in _assembliesToScan)
{
    Logger.DebugFormat(" * {0}", assembly);
    modelMapper.AddMappings(assembly.GetTypes());
}

Logger.InfoFormat("Adding {0} class maps", _classMaps.Count);
foreach (var type in _classMaps)
{
    Logger.DebugFormat(" * {0}", type);
    modelMapper.AddMapping(type);
}

var cfg = new Configuration();

ConfigureNHibernate(cfg, Settings[Type]);
ConfigureEnvironment(cfg);
cfg.AddMapping(modelMapper.CompileMappingForAllExplicitlyAddedEntities());

ValidateSchema(cfg);

SessionFactory = cfg.BuildSessionFactory();

Answer 1

Sounds like it could be related to this?

NHibernate - Wrong Columns on Queries

There's since been an update to the NHibernate source code (v 3.3.4), which should have fixed the problem.

See for more details: https://groups.google.com/forum/#!topic/nhusers/BZoBoyWQEvs