>>>Do you have DELETED() tags in both tables?
>>>
>>Yes
>>
>Surely, you have both tables indexed on MasterID?

Sorry if this is a dumb question. But...

To expand on Edward's question: you have a TAG in the Child Table whose expression is JUST MasterID, right? Not on MasterID+ChildID or something like that? If your Child's tag expression is MasterID+ChildID, then Child.MasterID = Master.MasterID is not optimizable.

But you probably know that.

HTH,