[deely3]

Primary key and quantity field could be not a perfect solution from performance point of view. Timestamps does not guarantee uniqueness.

Look, Im not trying to win the argument. In most cases you definitely right, my point is that sometime you have to work with working legacy code/system, and sometime this system could have some unique features.

[Dylan16807]

It's still not something you "want to have", it's something you might be forced to deal with because someone screwed up the design.

And ensuring you have a real primary key should only be good for performance, in the realm of SQL databases.