64-bits is plenty as long as you code it properly. The ids should be generated as part of the INSERT statement itself. This means in the rare case which has a d

64-bits is plenty as long as you code it properly. The ids should be generated as part of the INSERT statement itself. This means in the rare case which has a duplicate id generated, you will get a primary key error and the transaction will fail. In most cases this means user gets an error message and retries. If the above leads to any serious application problems, then you've got a lurking bug already, because you never know when there may be a network outage for example, and this would have the same effect.