No, I have to reason to believe that there is any such guarantee. While that would certainly be nice, I have to way of knowing whether that's true.

>>Fabio --
>>
>>I guess there were two pieces of relevant information I failed to include:
>>
>>(1) These are free-standing tables.
>>(2) They're not mine to modify.
>>
>>Thus, I have to use them with the structure they have now.
>>
>
>However they should have a combination of fields that they identify ogni record.