Fluent NHibernate misplaced duplicate field

Question

I think I'm misunderstanding something about how this works. This is my fluent mapping:

public class FunctionInfoMap : ClassMap<FunctionInfo>
 {
  public FunctionInfoMap()
  {
   Id(x => x.Id);
   Map(x => x.Name);
   Map(x => x.Signature);
   Map(x => x.IsNative);
   Map(x => x.ClassId);
   References(x => x.Class, "ClassId");
   HasMany(x => x.CallsAsParent).Inverse();
   HasMany(x => x.CallsAsChild).Inverse();
   Table("Functions");
  }
 }

 public class CallMap : ClassMap<Call>
 {
  public CallMap()
  {
   CompositeId()
    .KeyProperty(x => x.ThreadId)
    .KeyProperty(x => x.ParentId)
    .KeyProperty(x => x.ChildId)
    .Mapped();
   Map(x => x.ThreadId).Index("Calls_ThreadIndex");
   Map(x => x.ParentId).Index("Calls_ParentIndex");
   Map(x => x.ChildId).Index("Calls_ChildIndex");
   Map(x => x.HitCount);
   References(x => x.Thread, "ThreadId");
   References(x => x.Parent, "ParentId");
   References(x => x.Child, "ChildId");
   Table("Calls");
  }
 }

 public class SampleMap : ClassMap<Sample>
 {
  public SampleMap()
  {
   CompositeId()
    .KeyProperty(x => x.ThreadId)
    .KeyProperty(x => x.FunctionId)
    .Mapped();
   Map(x => x.ThreadId);
   Map(x => x.FunctionId);
   Map(x => x.HitCount);
   References(x => x.Thread, "ThreadId");
   References(x => x.Function, "FunctionId");
   Table("Samples");
  }
 }

Now when I create this schema into a fresh database, that FunctionId field from SampleMap winds up in the Calls table.

create table Calls (
        ThreadId INTEGER not null,
       ParentId INTEGER not null,
       ChildId INTEGER not null,
       HitCount INTEGER,
       FunctionId INTEGER,
       primary key (ThreadId, ParentId, ChildId)
    )

create table Samples (
    ThreadId INTEGER not null,
   FunctionId INTEGER not null,
   HitCount INTEGER,
   FunctionId INTEGER,
   primary key (ThreadId, FunctionId)
)

I don't understand why it's there, since it should only exist in the Samples table.

Answer 1

You should not map both the foreign key and the many-ton-one relationship. Instead of

   Map(x => x.ThreadId).Index("Calls_ThreadIndex");
   Map(x => x.ParentId).Index("Calls_ParentIndex");
   Map(x => x.ChildId).Index("Calls_ChildIndex");
   Map(x => x.HitCount);
   References(x => x.Thread, "ThreadId");
   References(x => x.Parent, "ParentId");
   References(x => x.Child, "ChildId");

map the many-to-ones which use the foreign keys

   Map(x => x.HitCount);
   References(x => x.Thread, "ThreadId");
   References(x => x.Parent, "ParentId");
   References(x => x.Child, "ChildId");

I don't know if this will solve your problem. Also, I strongly advise against using composite keys. Replace them with surrogate key (identity) and unique indexes.