Why Are Different Query Results Returned After I Use Same Query Criteria to Query Data Successfully Imported by HBase bulkload?

Question

If the data to be imported by HBase bulkload has identical rowkeys, the data import is successful but identical query criteria produce different query results.

Answer

Data with an identical rowkey is loaded into HBase in the order in which data is read. The data with the latest timestamp is considered to be the latest data. By default, data is not queried by timestamp. Therefore, if you query for data with an identical rowkey, only the latest data is returned.

While data is being loaded by bulkload, the memory processes the data into HFiles quickly, leading to the possibility that data with an identical rowkey has a same timestamp. In this case, identical query criteria may produce different query results.

To avoid this problem, ensure that the same data file does not contain identical rowkeys while you are creating tables or loading data.