[HIVE-15486] DefaultGraphWalker invokes getChildren() as many times as there are children

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.0.0, 2.1.0
• Component/s: Query Processor
• Assignee: Dhiraj Kumar
• Reporter: Dhiraj Kumar
• Created: 21/Dec/16 14:16
• Updated: 15/Feb/17 18:44

Description

DefaultGraphWalker while walking a Node, calls up getChildren method as many times as there are children. This leads a performance penalty where a node has too many direct children.

Attached is query file. Instruction to run

1. time hive -f query

Checkout the time on hive 1.2 version vs 2.1 version.

This change was introduced in HIVE-11652