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

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 0.9.0
• Fix Version/s: 0.13.0
• Component/s: HBase Handler
• Labels: patch

Environment

All Platforms

• Assignee: Unassigned
• Reporter: Karthik Kumara
• Created: 28/Mar/13 20:06
• Updated: 22/Sep/13 08:23
• Resolved: 22/Sep/13 08:23

Description

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.

Issue Links

• duplicates: HIVE-3420 Inefficiency in hbase handler when process query including rowkey range scan