[HIVE-24239] Reduce side chain of Map join produce wrong result

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.1.0
• Component/s: llap
• Assignee: Unassigned
• Reporter: Manoj Kumar
• Created: 07/Oct/20 09:35
• Updated: 07/Oct/20 09:35

Description

Getting the wrong result on multiple queries.

On further debug it seems queries follow a common pattern on reduce side chain of mapjoin.

[Observation]
If we have a chain of mapjoin on the reduce side, each mapjoin gets side tables as buckted.
Ideally in a chain of map joins we should get side table as broadcast except for the first side table.

Attaching pla of TPCH Q5 for reference.