[SomeRandomUser]

I've never worked with big databases so bare with me if this is a really silly question.

Let's say I have database A with sequential IDs, and database B with sequential IDs. Couldn't I just translate the sequential IDs to GUIDs in both databases, merge them to database C and then translate the records from A and B to sequential IDs?

Or modyfying IDs is a big no-no in this scenario?

[zrail]

Modifying IDs is a giant pain in the ass. At several previous jobs we've had to rekey billions of records with sequential IDs and it never ever goes correctly the first (or tenth) time, and when it eventually does work it takes forever to complete.