Its never a bad idea to have a guaranteed unique row identifier. I guess I shouldn't say never - but lets go with the overwhelming majority of the time its a good idea.

Theoretical potential downsides include an extra index to maintain and extra storage space used. That's never been enough of a reason to me to not use one.

It's never a bad idea to have a guaranteed unique row identifier. I guess I shouldn't say never – but let's go with the overwhelming majority of the time it's a good idea.

Theoretical potential downsides include an extra index to maintain and extra storage space used. That's never been enough of a reason to me to not use one.