Can we use an "Id" with a data type other than String?

[MartinRobins]

The PK on most of my (SQL Server) tables is of type "int", and some are "bigint" due to the expected number of rows.
Is it possible to use these tables within the synchronisation service without having to create any alternative PK?

[ahallctr-jpg]

No.

int types (and, by extension, bigint) are not suitable because they are not globally unique. You also don't get an auto-increment capability in the mobile world.

One thing you CAN do is to have a GUID Id and an int PkId that is not exposed to the user. The PkId is int/auto-increment on first store; the Id is generated when not provided.