The version is just an atomic integer assigned to that btree node which is monotonically increasing. Each writer increases the version when it releases the lock IF it has modified the node.
Wraparounds are only a theoretical issue. There would have to be exactly UINT64_MAX writers between a reader first checking the version and verifying the version.
Wraparounds are only a theoretical issue. There would have to be exactly UINT64_MAX writers between a reader first checking the version and verifying the version.