HBASE-11544 allow scan rpc return partial of a row to reduce memory usage for one rpc request. And client can setAllowPartial or setBatch to get several cells in a row instead of the whole row.
However, the status of the scanner is saved on server and we need this to get the next part if there is a partial result before. If we move the region to another RS, client will get a NotServingRegionException and open a new scanner to the new RS which will be regarded as a new scan from the end of this row. So the rest cells of the row of last result will be missing.