[jira] [Created] (HIVE-4247) Filtering on a hbase row key duplicates results across multiple mappers

["Karthik Kumara (JIRA)" <ji...@apache.org>]

Karthik Kumara created HIVE-4247:
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             Summary: Filtering on a hbase row key duplicates results across multiple mappers
                 Key: HIVE-4247
                 URL: https://issues.apache.org/jira/browse/HIVE-4247
             Project: Hive
          Issue Type: Bug
          Components: HBase Handler
    Affects Versions: 0.9.0
         Environment: All Platforms
            Reporter: Karthik Kumara


Steps to reproduce
1. Create a Hive external table with HiveHbaseHandler with enough data in the hbase table to spawn multiple mappers for the hive query.
2. Write a query which has a filter (in the where clause) based on the hbase row key. 
3. Running the map reduce job leads to each mapper querying the entire data set.  duplicating the data for each mapper. Each mapper processes the entire filtered range and the results get multiplied as the number of mappers run.

Expected behavior:
Each mapper should process a different part of the data and should not duplicate.


Cause:
The cause seems to be the convertFilter method in HiveHBaseTableInputFormat. convertFilter has this piece of code which rewrites the start and the stop row for each split which leads each mapper to process the entire range

 if (tableSplit != null) {
      tableSplit = new TableSplit(
        tableSplit.getTableName(),
        startRow,
        stopRow,
        tableSplit.getRegionLocation());
    }

The scan already has the start and stop row set when the splits are created. So this piece of code is probably redundant.
 

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