[HIVE-3511] Constant values in aggregation parameters should not be attached to every map output row

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Yin Huai
• Created: 28/Sep/12 00:17
• Updated: 28/Sep/12 00:48
• Resolved: 28/Sep/12 00:48

Description

When map-side-aggregation is disabled (hive.map.aggr=false), constant values in aggregation parameters are attached to every map output row. For example, in test case 'count.q' (https://github.com/apache/hive/blob/trunk/ql/src/test/results/clientpositive/count.q.out). For count(1), if hive.map.aggr=false, '1' will be attached to every output row of ReduceSinkOperator.

Issue Links

• duplicates: HIVE-757 Don't send constants from mapper to reducer for Group By queries