A RowBatch does not support serializing an uncompressed size of greater than INT_MAX. The serialization format relies on tuple offsets of type of int32, so they cannot address greater than INT_MAX.
On debug builds, a DCHECK in SerializeInternal() fires when the size exceeds INT_MAX. On release builds, LZ4's limitation of INT_MAX on the size of uncompressed size avoids any issue. The serialization codepath should protect itself and avoid this issue on debug builds.