private void FindDroppedUniqueConstraints(
Tuple <IEntityType, IEntityType> tablePair,
IEnumerable <Tuple <IKey, IKey> > uniqueConstraintPairs)
{
var pk1 = tablePair.Item1.TryGetPrimaryKey();
_operations.AddRange(
tablePair.Item1.Keys.Where(k => k != pk1)
.Except(uniqueConstraintPairs.Select(pair => pair.Item1))
.Select(uc => OperationFactory.DropUniqueConstraintOperation(uc)));
}